Arctic Sea Ice : Forum

Cryosphere => Antarctica => Topic started by: b_lumenkraft on February 21, 2019, 04:14:14 PM

Title: The Amery Ice Shelf Thread
Post by: b_lumenkraft on February 21, 2019, 04:14:14 PM
Resuming conversation from

New clear Sentinel pics today.

Link >> https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=-71.61099038970809&lng=69.23789978027344&zoom=13&preset=CUSTOM&layers=B01,B02,B03&maxcc=20&gain=1.0&gamma=1.0&time=2018-08-01%7C2019-02-21&atmFilter=&showDates=false&evalscript=cmV0dXJuIFtCOEEqMSxCMDMqMSxCMDIqMV0%3D

Indeed the big melt pond is now frozen but with pretty blue cracks visible. I wonder if it's melting again. (pic1)

Upstream the melt ponds are still blue. (pic2)
Title: Re: The Amery Ice Shelf Thread
Post by: Stephan on February 21, 2019, 06:07:44 PM
Thanks for opening this thread. I think Améry should gain more attention than it received so far in this forum.
Title: Re: The Amery Ice Shelf Thread
Post by: b_lumenkraft on February 21, 2019, 06:13:25 PM
Agreed Stephan. :)

Since Neven never opposed i just went for it! ;)
Title: Re: The Amery Ice Shelf Thread
Post by: oren on February 22, 2019, 01:31:57 AM
Thanks for opening this thread. I think Améry should gain more attention than it received so far in this forum.
+1, although I hope it stays calm and cool and loses attention...
Title: Re: The Amery Ice Shelf Thread
Post by: maga on September 25, 2019, 09:11:07 PM
Big claving at Amery!
Title: Re: The Amery Ice Shelf Thread
Post by: blumenkraft on September 25, 2019, 09:27:00 PM
Wow!  :o
Title: Re: The Amery Ice Shelf Thread
Post by: Stephan on September 25, 2019, 10:05:40 PM
Wow  :o
That is huge, and probably not seen there for a while ?!? [Haven't checked the calving history of this ice shelf]
Title: Re: The Amery Ice Shelf Thread
Post by: sidd on September 25, 2019, 11:08:17 PM
I have been worried about Amery for a while. I have been seein sporadic reports of warm water offshore. The ice profile in that basin is concave upward and the thing is like a dagger pointed into the heart of antarctica.

sidd
Title: Re: The Amery Ice Shelf Thread
Post by: oren on September 26, 2019, 03:46:50 AM
A quick and dirty Worldview animation shows that the ice shelf forward progress since the year 2000 was less than half of the calve width, so I would say this sets back Amery ~40 years. Hopefully this is cyclical and the next 20 years will see Amery back to its year 2000 position.
If someone has access to older satellite images of the shelf this could be improved.

In addition, this article (linked from Wikipedia) (https://www.abc.net.au/news/2006-12-08/australians-to-study-giant-antarctic-ice-cracks/2149650) says the following:
Quote
Australians to study giant Antarctic ice cracks
Updated 20 Dec 2006, 7:39am

Hobart scientists are heading to Antarctica to study the cause of enormous cracks forming in the Amery Ice Shelf.

The cracks began forming around a decade ago and are growing at three to five metres a day.

The fractures threatened to break off a 900-square-kilometre piece of the Amery Ice Shelf, which is about the size of Tasmania.

Scientists want to know what is causing these cracks, as the last recorded activity in this part of eastern Antarctica was in the 1960s.

The head of the research, Professor Richard Coleman, says there is not enough evidence to blame global warming.

"It may be in a 50- to 60-year cycle but we would need more data to say whether it's increasing in terms of calving events due to warming of the ice shelf," he said.

Professor Coleman says with the ice already floating, it will not increase ocean levels.

As the new calving is roughly 900 km2 (eyeballing maga's image), this could be the result of a very long process.
Title: Re: The Amery Ice Shelf Thread
Post by: IceConcerned on September 26, 2019, 11:53:44 AM
The speed of this calving is properly astonishing : I was having  alook from time to ime to the shelf, and the big cracks showed no really active propagation
For example see Sentinel image (from Polarview) on Sept.23 :
https://www.polarview.aq/images/105_S1jpgfull/S1A_IW_GRDH_1SSH_20190923T154447_5F29_S_1.final.jpg (https://www.polarview.aq/images/105_S1jpgfull/S1A_IW_GRDH_1SSH_20190923T154447_5F29_S_1.final.jpg)
Title: Re: The Amery Ice Shelf Thread
Post by: blumenkraft on September 26, 2019, 07:11:03 PM
And to make the collection complete, here is the Sentinel radar, 20. vs 25.

Title: Re: The Amery Ice Shelf Thread
Post by: Stephan on September 26, 2019, 08:59:10 PM
Thank you blumenkraft and Oren for these movies.
Compared to PIIS and Thwaites Amery seems to be at least half a tens potency slower.
Title: Re: The Amery Ice Shelf Thread
Post by: blumenkraft on September 26, 2019, 09:07:39 PM
Welcome, Stephan. :)
Title: Re: The Amery Ice Shelf Thread
Post by: vox_mundi on October 01, 2019, 06:34:17 AM
Giant Iceberg Breaks Off East Antarctica
https://www.theguardian.com/world/2019/oct/01/giant-iceberg-breaks-off-east-antarctica

The tabular iceberg, officially named D-28, separated from the Amery ice shelf on 26 September. The iceberg is 1,636 square kilometres in size, or about 50 x 30km, the Australian Antarctic Division said.

It is the first major calving event on the Amery ice shelf since 1963-64.

https://youtu.be/mA9dooj1_0I
Title: Re: The Amery Ice Shelf Thread
Post by: blumenkraft on October 01, 2019, 06:47:51 AM
Actually, it broke off between 24th and 25th, not 26.

Also, the morphing thingy the Guardian did with their GIF is weird. Gives a wrong impression of what happened.

With ASIF you get a timely and correct reporting with accurate GIFs.  :P
Title: Re: The Amery Ice Shelf Thread
Post by: sidd on October 07, 2019, 02:15:38 AM
Last year, Alley et al. (doi: 10.1016/j.rse.2018.03.025 )  valued antarctic ice shelf vulnerability to hydrofracture. The measure of vulnerability is the fraction of ice saturated firn.

Amery is disquieting, The first figure attached shows the Amery Shelf in panel a (panel b is the Roy Baudouin shelf)

Today ASLR informs of Stokes et al. (doi : 10.1038/s41598-019-50343-5 ) who superpose supraglacial lake images on those vulnerable areas. Amery is even more disquieting. The second figure attached shows Amery in panel b.
The lakes are in black, the grounding lines in red.

sidd