Halley base shut down and new crack in Brunt shelf

[Stephan]

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...

[b_lumenkraft]

For how i understand it, to become loose, it also needs to melt from the bottom.

[interstitial]

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]

Welcome, Interstitial.

[solartim27]

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

[FredBear]

Cloudy image on    arctic.io   today (2020-02-14) - but has the end of Brunt ice shelf fallen off & drifted south?

[blumenkraft]

Yes, i think so.

Hard to see but in the image of the 14th there is ice melange indicating a calving.

[FredBear]

Brunt - False alarm - sorry!

[blumenkraft]

Well, a little bit came off after all. 

[Andreas T]

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]

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]

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??

[baking]

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]

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]

New Sentinel 1 image posted from
https://twitter.com/JanWuite/status/1311007660930719745?s=19  Some nice videos by Stef Lhermitte upthread.

[paolo]

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]

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]

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]

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.

[interstitial]

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]

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