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Author Topic: Halley base shut down and new crack in Brunt shelf  (Read 45894 times)

Stephan

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #100 on: June 15, 2019, 11:35:42 AM »
OK. I could not detect this tiny crack in the animation above.
Nevertheless I wonder about the stability of all the ice with a lot of thick cracks W and N of that ice rumple. In my lay man opinion it should have calved already...
It is too late just to be concerned about Climate Change

b_lumenkraft

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #101 on: June 15, 2019, 12:15:42 PM »
For how i understand it, to become loose, it also needs to melt from the bottom.

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #102 on: June 15, 2019, 11:57:39 PM »
That makes more sense. I saw several cracks that I thought should let it break free but the just seemed to get snowed over and disappear. Thanks BL

b_lumenkraft

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #103 on: June 16, 2019, 05:35:16 AM »
Welcome, Interstitial. :)

solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #104 on: January 24, 2020, 04:35:44 PM »
Well, this has taken longer than I expected.  I'm going to go on a ledge and say this summer for sure.
Here's a link to Bert Wouters latest tweet
https://twitter.com/bert_polar/status/1216852873788653568?s=19
35 Mb image https://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20200123T233940_DC58_S_1.final.jpg
« Last Edit: January 24, 2020, 04:50:27 PM by solartim27 »
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FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #105 on: February 14, 2020, 05:15:17 PM »
Cloudy image on    arctic.io   today (2020-02-14) - but has the end of Brunt ice shelf fallen off & drifted south?

blumenkraft

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #106 on: February 14, 2020, 05:50:39 PM »
Yes, i think so.

Hard to see but in the image of the 14th there is ice melange indicating a calving.
« Last Edit: February 14, 2020, 07:19:24 PM by blumenkraft »

FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #107 on: February 15, 2020, 11:12:04 AM »
Brunt - False alarm - sorry!

blumenkraft

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #108 on: February 16, 2020, 01:12:39 PM »
Well, a little bit came off after all.  ;D ;D ;D

Andreas T

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #109 on: February 16, 2020, 07:08:57 PM »
nor has Chasm 1 connected to one of the cracks west of that ice rumple.

Sorry, Stephan, i have to correct you.

Chasm1 has cracked all the way to the rumple now.

I'm expecting calving any time now.
any time = any number of months I guess.
I cobbled this gif together from blumenk's image and the S1A from today. It required scaling which I did by trying to match distances in the vertical (Y) direction, so the more distant movement may be to large or too small.
But what shows, I think is that the movement is driven from a push of the shelf past the ice rumple rather than a pull of the nearly detached piece. There is widening of the crack further south west (beyond the frame)
I find it entirely possible that this won't detach fully for another season at least. But that is as much of a guess as anybody elses

blumenkraft

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #110 on: February 16, 2020, 07:19:45 PM »
any time = any number of months I guess.

Exactly! Just like PIG! ;)

So sorry for the BS i said there, Andreas. I was too young back then.

But since you said it can hold another season, i expect it to calve any moment now. ;)

Stephan

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #111 on: February 16, 2020, 08:35:51 PM »
It might be necessary that the Haloween Crack expands further west and pass the ice rumples to destabilize the SW part of the Brunt Ice Shelf so that a calving can take place??
It is too late just to be concerned about Climate Change

baking

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #112 on: February 17, 2020, 09:06:32 PM »
There is a particular Sentinel-1B orbit that runs parallel to the crack that is particularly good at picking at details, probably because the side aperture radar is close to perpendicular to the crack.  I started watching this crack back in April and I compare my oldest image to the newest one in this GIF.

Zoom in on the center of the image.  Even though things are obviously moving, cracks are widening, new cracks are forming, it doesn't really seem that much closer to calving if you look at how far away the cracks on either side are.  The newest image is due tonight at midnight UTC so maybe we will see some change, but this one is a slow mover so don't get too excited.

IceConcerned

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #113 on: February 28, 2020, 10:41:22 PM »
When looking at the last Sentinel SAR image I tend to concur : the iceberg is detaching
Besides, a "parllel" to halloeen crack is developing
Both are underlined in the attached image

solartim27

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #114 on: September 29, 2020, 08:53:43 PM »
New Sentinel 1 image posted from
https://twitter.com/JanWuite/status/1311007660930719745?s=19  Some nice videos by Stef Lhermitte upthread.
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paolo

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #115 on: September 29, 2020, 10:05:34 PM »
But we can do better, using Sentinel1 images directly without waiting for their publication on Twitter. Even better, given the season, we can use Sentinel2 images. ;)

Attached a zoom on the still intact part between the two rifts (today's image)

nukefix

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #116 on: October 21, 2020, 04:48:50 PM »
For best sensitivity one should do S-1 interferograms to detect propagation of hairline cracks that are much smaller than the resolution of S-1 or S-2. There are free tools for doing this from ESA but the process is complex with a steep learning curve.

FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #117 on: November 23, 2020, 01:53:57 PM »
Planned Halley team visit leaving from Harwich 05/11/2020:-
"From Rothera, a team of 10 staff will fly to Halley Research Station to spend four to six weeks collecting data, servicing the scientific instruments and maintaining the station infrastructure before flying back to Rothera. At Halley, core scientific data can be collected year-round through the Halley Automation Project. Autonomous scientific equipment around the station and on the Brunt Ice Shelf collects information on weather, climate and the ozone."

https://www.bas.ac.uk/media-post/rrs-james-clark-ross-departs-for-antarctica

grixm

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #118 on: January 04, 2021, 06:58:12 PM »
Animated comparisons of today's clear sentinel images, and almost one year ago. Click to play.

The main rift has widened significantly, but not lenghtened very much, even filled back with snow at the edge it looks like.. However, the smaller rifts coming to meet it from the north *have* lengthened some.

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #119 on: January 05, 2021, 09:09:52 AM »
I was sure it was going to break off a year ago but that is before I became aware of the bathymetry. Their is an underwater protrusion underneath the tip making it difficult for it to just float away.

FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #120 on: January 16, 2021, 12:53:52 AM »
New BBC item on Brunt/Halley:-

https://www.bbc.co.uk/news/science-environment-55573397

Also BAS audio comments on ozone hole measurements there this year:-

https://www.bbc.co.uk/news/topics/cezwlwl6j43t/british-antarctic-survey
« Last Edit: January 16, 2021, 01:34:05 AM by FredBear »

iwantatr8

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #121 on: January 19, 2021, 05:40:54 PM »
Hi Folks,

Just a reminder to check the CPOM site over the next few days..

http://www.cpom.ucl.ac.uk/csopr/brunt/


iwantatr8

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grixm

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #123 on: January 31, 2021, 08:53:09 AM »
Indeed, if we zoom in enough, we can see that the "New Crack" has already almost reached the other side. It's expanding super fast.

grixm

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #124 on: February 02, 2021, 09:45:56 PM »
Update, the New Crack has grown even more this week. I added in green the crack extension of today's image since the last image. And also the little crack below it has also grown, so I added green there too.

Stephan

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #125 on: February 05, 2021, 07:53:41 PM »
I just found this little history of the various Halley research stations on the Brunt Ice Shelf in a philatelistic journal (Michel-Rundschau 2/2021). It is not a scientific article (of course) but it describes the various moves these stations had to make. Also the growth of Chasm I and Halloween Crack in the last years are mentioned.
If you can not read German you may enjoy the beautiful stamps of the British Antarctic Territory, a small number of them have been chosen to illustrate the beauty and the remoteness of this outpost in the white wilderness.
It is too late just to be concerned about Climate Change

grixm

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #126 on: February 12, 2021, 08:15:50 PM »
Another update on the New Crack. It has extended a little bit, and also started to grow some branches.

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #127 on: February 12, 2021, 08:38:10 PM »
https://tc.copernicus.org/articles/13/545/2019/#&gid=1&pid=1
article on brunt ice shelf bathymetry

If you look at figure 4D it shows probable pinning points. They go a long way to explain why it has taken so long for Brunt Ice shelf to break off and why it is unlikely to float away anytime soon.

FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #128 on: February 26, 2021, 03:32:37 PM »
BBC finally announces the break in the Brunt ice shelf:-

https://www.bbc.co.uk/news/science-environment-47692895

British Antarctic Survey say that it is the north rift that has broken through not the chasm 1 :-

https://www.bas.ac.uk/media-post/brunt-ice-shelf-in-antarctica-calves
« Last Edit: February 26, 2021, 03:38:57 PM by FredBear »

paolo

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #129 on: February 26, 2021, 04:30:45 PM »
Indeed one could already see it in the Sentinel1 high definition image of the 24/02/2021.

We were not good on this one.

Very large image, sorry

grixm

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #130 on: February 26, 2021, 04:40:17 PM »
Indeed one could already see it in the Sentinel1 high definition image of the 24/02/2021.

We were not good on this one.

Very large image, sorry

I marked part of these extensions on my previous sentinel2 overlay, and I had seen these sentinel1 images too, but I didn't think it looked conclusive. Last good view of that crack we got, the main crack did not actually connect with the one coming from the north, they were going past each other. And therefore it was IMO not possible to know whether they were connected on the sentinel1 image either, or whether the main crack would continue growing east instead.

paolo

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #131 on: February 26, 2021, 05:02:32 PM »
Rapid measurement of the iceberg's surface at calving time: 1262 km2

Tor Bejnar

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #132 on: February 26, 2021, 07:32:45 PM »
I've been known to see things that aren't there, but I've circled what might be the extension of the 'left' crack.
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FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #133 on: February 26, 2021, 07:38:08 PM »

We were not good on this one.

But BAS have the advantage of all those GPS sensors (+ maybe much more!)

paolo

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #134 on: February 26, 2021, 08:38:17 PM »
I don't understand why we are discussing the Sentinel2 image of 12/02, an image in which the rift is not complete!
What we didn't see is the development of the rift in the Sentinel1 image of 24/02, even if in many lines it is only a weak signal from the thickness of a pixel (that's why I posted the image in its real size without reducing it).
Indeed, blasé by the expected calvings that didn't arrive, and knowing that Grixm was regularly following and posting beautiful images relating to the development of the rift, I looked too quickly and concluded that there was nothing to report. 
After a careful analysis of this image one should have concluded that the rift was complete or on the way to being complete very quickly!
What leaves me a little dreamy is not that I did not see, but that nobody saw.

FredBear,
but we're the best  ;)

grixm

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #135 on: February 26, 2021, 09:37:36 PM »
I don't understand why we are discussing the Sentinel2 image of 12/02, an image in which the rift is not complete!
What we didn't see is the development of the rift in the Sentinel1 image of 24/02, even if in many lines it is only a weak signal from the thickness of a pixel (that's why I posted the image in its real size without reducing it).
Indeed, blasé by the expected calvings that didn't arrive, and knowing that Grixm was regularly following and posting beautiful images relating to the development of the rift, I looked too quickly and concluded that there was nothing to report. 
After a careful analysis of this image one should have concluded that the rift was complete or on the way to being complete very quickly!
What leaves me a little dreamy is not that I did not see, but that nobody saw.

FredBear,
but we're the best  ;)

The thing is: Was there really any development in the rift in the image from the 24th? I'm not sure that can be concluded, even in hindsight, because of the image quality. The faint lines might not actually be connected all the way, or even just be a phantom of image compression. So there may not actually have been any development from the 12th to the 24th. In fact the BAS article says that the calving did not happen until later: "The iceberg was formed when the crack widened several hundred metres in a few hours on the morning of 26th Feb, releasing it from the rest of floating ice shelf."

I may just be nitpicking, but nitpicking is fun :)

paolo

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #136 on: February 26, 2021, 11:45:33 PM »
Now we have today's Sentinel2 picture it's rotten,

but it's clear on the final part of the rift.
 :) :)

Click to enlarge

FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #137 on: February 27, 2021, 12:43:07 AM »
BAS called this one - they had the instrumentation and the survey on the site for an instant response - we are no competition.
It is not just the moment of birth that counts for this iceberg - it's what happens next as well.
For example A23A was born "nearby" from the Filchner Ice Shelf in August 1986, but has only moved around 200 km (125 mi) in 31 years because it is grounded on the sea floor and is currently the largest iceberg:-
https://www.guinnessworldrecords.com/world-records/81727-largest-iceberg
(A23A has been wriggling around this past year - beginning in the dark of winter - so it may have no firm attachment to the sea floor any more?)

I was rather expecting any calving to happen later in the dark, but it didn't wait.
I think "interesting" things may happen both to the Brunt ice shelf and the icebergs during the long winter night, just to try to surprise us when the sun comes back in September?
(Compare with the apocryphal curse "May you live in interesting times")

baking

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grixm

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #139 on: February 27, 2021, 01:13:12 PM »
The iceberg has drifted a bit further out since yesterday.

Stephan

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #140 on: February 27, 2021, 06:46:00 PM »
Thank you for that animation.
So we have a new huge iceberg.
What does this mean to Brunt Ice Shelf? Will the flow direction change? Will the Halloween Crack widen because there is much less resistance to the North? Or will this loss stabilize the rest because much less weight and area is involved?
It is too late just to be concerned about Climate Change

grixm

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #141 on: February 28, 2021, 11:24:31 AM »
Sentinel-1 before and after images. Doesn't look like the other cracks were affected by the calving at all, at least not yet.

paolo

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #142 on: March 01, 2021, 01:25:49 PM »
An update of the new iceberg and a detailed and annotated image (2200x4200) of the Brunt Ice Shelf.

Twice click to enlarge

FredBear

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #143 on: March 01, 2021, 02:16:25 PM »
Paolo, that break-up in the north edge of the new iceberg is helping free up/push the whole lot out to sea. It has also tidied up the north edge for the moment (where there were different cracks which could have delineated the margin of the iceberg). Will much more break away??
« Last Edit: March 01, 2021, 03:10:17 PM by FredBear »

paolo

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #144 on: March 01, 2021, 02:49:35 PM »
The pieces that are breaking off to the north of the iceberg are thick sea ice that filled the Brunt-Stancomb Chasm, so they are not really part of the Ice Shelf, nor of the iceberg.
The old position of this chasm is visualised by the grey colour, the chasm having since moved with the Ice Shelf towards North-West.
I think, as I indicated, that the emptying of the chasm could destabilize in the future the block that delimits to the North-East this chasm, a block that is part of the Strancomb-Wills Glacier Tongue.

PS : FredBear : Paolo

Phil42

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #145 on: March 04, 2021, 10:58:48 AM »
NASA Earth posted this nice image on their twitter and I thought it might be worth sharing. Of course it's not as detailed as paolo's analysis but it gives a nice overview of just how gigantic this iceberg is.



Source

Stephan

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #146 on: March 04, 2021, 07:05:49 PM »
Thanks for sharing, Phil.  :)
It is too late just to be concerned about Climate Change

gerontocrat

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #147 on: March 05, 2021, 07:44:59 PM »
Super dooper images from https://www.bbc.co.uk/news/science-environment-56294690

Antarctica: Close-up view of crack that made mega-iceberg


The North Rift pictured last Saturday. The gap is about 2km wide



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Espen

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #148 on: March 08, 2021, 04:11:36 PM »
Here is another:

Please click on image to animate and enlarge!
Have a ice day!

iwantatr8

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Re: Halley base shut down and new crack in Brunt shelf
« Reply #149 on: March 09, 2021, 02:55:46 PM »
What's interesting about that Espen is that following the calving of A74, the mouth of Crack 1 gets a small calving and the major burg-to-be rotates clockwise slightly increasing the width of Crack 1.  This is evidenced in the small sea-ice cracks midway down the crevasse.