Support the Arctic Sea Ice Forum and Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - Andreas T

Pages: [1]
1
Antarctica / Re: Halley base shut down and new crack in Brunt shelf
« 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

2
Policy and solutions / Re: Renewable Energy
« on: February 11, 2020, 12:39:57 AM »
With strong winds here in the UK over the weekend I have been watching the wind power data on https://gridwatch.co.uk/Wind to see whether there might be a new record in power generated. That did not happen, I think that maximum was reached on 7th of January but it looks like today could have been the 24h period with the highest average generation (12.7 GW according to gridwatch which does not include some smaller scale generation)
Can somebody confirm or correct this?

3
Antarctica / Re: Thwaites Glacier Discussion
« on: December 23, 2019, 08:53:46 PM »
not sure where this belongs so I quote myself
this is from cavity camp on the ice tongue.
Quote
After snowfall bound us to our tents for the last three days, clear blue skies and crisp conditions allowed the first field measurements on the Thwaites Glacier today. The ice is generally thinner than we have estimated from satellite data before coming to Antarctica. This is important because it indicates a change in the structural stability of this part of Thwaites Glacier. Underneath our camp, ice thickness is just about 300m, followed by 550m of ocean water to the sea floor.
https://polarchristian.com/2019/12/23/first-field-measurements-are-surprising/
Attached image is from
https://www.pnas.org/content/116/38/18867
Multidecadal observations of the Antarctic ice sheet from restored analog radar records
image shows:
Quote
Three decades of change beneath the eastern ice shelf of Thwaites Glacier. (A) Map showing the locations of the 2009 OIB (purple lines) and 300-MHz 1978 SPRI radar profiles (orange line) with colored dots showing intersection locations. Black line shows the contemporary grounding line. (B) The SPRI sounding profile scanned from 1978 analog data. (C) An OIB radar-sounding profile from 2009, which crosses the 1978 line near the grounding line (green square). (D) An additional OIB radar-sounding profile from 2009, which crosses the 1978 line near the regrounding point (yellow square). Widths of the colored squares correspond to the uncertainty in intersection locations. All 3 profiles show a grounded inland ridge, the inland extent of basal crevassing, and the regrounding of the ice shelf on an offshore ridge (28). (E) The floating portion of the ice shelf (seaward of basal crevassing as indicated by the red bars) thinned from 527 ± 43 m to 412 ± 45 m in 30 y. (F) In the same period, the regrounded portion of the ice shelf remained relatively stable, thickening by 19 ± 43 m

4
Arctic background / Re: Antarctic Expeditions
« on: December 23, 2019, 08:30:40 PM »
this is from cavity camp on the ice tongue.
Quote
After snowfall bound us to our tents for the last three days, clear blue skies and crisp conditions allowed the first field measurements on the Thwaites Glacier today. The ice is generally thinner than we have estimated from satellite data before coming to Antarctica. This is important because it indicates a change in the structural stability of this part of Thwaites Glacier. Underneath our camp, ice thickness is just about 300m, followed by 550m of ocean water to the sea floor.
https://polarchristian.com/2019/12/23/first-field-measurements-are-surprising/

5
Antarctica / Re: Thwaites Glacier Discussion
« on: December 21, 2019, 09:59:03 AM »
its not stated explicitly but this seems to show snow accumulation at the grounding zone drill site.
https://pbs.twimg.com/media/EMLFPE1WwAEseyC.jpg:large
on a slow moving ice shelf this will build up over years I guess. I read about this process on the Brunt ice shelf where time scales are very long.
source:
https://twitter.com/HotWaterOnIce/status/1207744520080830465
Quote
hat do you get when you leave an instrument to over winter in an area that gets lots of snow🌨️🌨️🌨️….? A whole day of back breaking digging – especially when you don’t start digging in the right place😖!

6
Arctic background / Re: Antarctic Expeditions
« on: December 14, 2019, 07:27:03 PM »
the expedition season in antarctica has started
some links have been posted elsewhere but are probably easier to find here
https://thwaitesglacier.org/news
some great up to date photos and details about working next to pine island glacier, enough to make one a little envious
https://twitter.com/geologicalJo
on the other side of PIG preparing for drilling near Thwaites eastern side

https://twitter.com/Alpinesciences/status/1204548226466156546


also on twitter
https://twitter.com/GlacierThwaites
https://twitter.com/HotWaterOnIce
these are locations we will hear from I hope

7
Antarctica / Re: Thwaites Glacier Discussion
« on: November 24, 2019, 10:08:31 PM »
B22A has been moving more than it has in the last few years I think. This has of course not much significance since it is just a stranded iceberg but as a start to the season it makes one wonder what effect it may have on the fast ice between it and the coast.
https://go.nasa.gov/2DeQwLr

8
Arctic background / Re: Antarctic Expeditions
« on: March 09, 2019, 03:02:50 PM »
A new post is up  on https://thwaitesglacieroffshoreresearch.org/news/2019/3/8/life-on-the-research-icebreaker-nathaniel-b-palmer
which has short clips on the ice edge of Thwaites Glacier Ice shelf (thats what the caption says) It would be nice to have more detail on the location of these images but nice to see what the white bits we see in the satellite images look close up.
Tasha Snow also has a new post up, interesting background to the research going on
https://thwaitesglacier.org/blog/snow-ice-geology-spoon-7
The NBP has moved on to the PIG according to sailwx by the way
https://www.sailwx.info/shiptrack/shipposition.phtml?call=WBP3210

9
Arctic background / Re: Antarctic Expeditions
« on: March 05, 2019, 10:47:09 PM »
A new entry on the THOR cruise news about their trip to Rothera with many nice photos:
https://thwaitesglacieroffshoreresearch.org/news/

10
Antarctica / Re: Thwaites Glacier Discussion
« on: February 28, 2019, 04:00:18 PM »
This (marked by X) is where the Nathaniel B Palmer is today according to sailwx, S 74°54' W 107°18'. It probably be a while before we hear details of the research there, but the blog posts have a lot of information.
North marked for orientation.
https://thwaitesglacier.org/blog

11
Arctic background / Re: Antarctic Expeditions
« on: February 26, 2019, 02:06:17 AM »
The N B Palmer is back off Pine island Glacier according to sailwx.
a post from the 24th is probably about activities before the detour to Rothera.
https://thwaitesglacieroffshoreresearch.org/news/2019/2/24/island-days-part-ii-tarsan-partners-with-the-natives-seals

but contains a lot of interesting information about the research.

12
Arctic background / Re: Antarctic Expeditions
« on: February 21, 2019, 12:11:34 PM »
Tasha Snow writes  about water temperature measurements, it obviously will take some time until those come out but getting access  below the ice with the AUV is really promising.
https://thwaitesglacier.org/blog
Since then the Nathaniel B Palmer has gone to Rothera station it seems from sailwx
https://www.sailwx.info/shiptrack/shipposition.phtml?call=WBP3210


13
Arctic background / Re: Antarctic Expeditions
« on: February 18, 2019, 10:15:12 PM »
here is a blog by one of the scientists on the way to Thwaites glacier:
https://thwaitesglacier.org/blog/snow-ice-ice-4

The Polarstern has left Punta Arenas and is heading for the Wedell sea
https://www.awi.de/en/expedition/ships/polarstern.html

14
Antarctica / Re: PIG has calved
« on: February 17, 2019, 11:03:04 PM »
Here are some pictures of research in Pine island bay happening now. I had not realised that there are parts which get free of snow in the summer.
https://www.facebook.com/thwaitesglaciercollaboration/?fref=mentions&__tn__=K-R

I assume these were taken on the Lindsay islands mentioned in an earlier post
http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=apollodata/data_polarview_apollodata/ahf/S2B_MSIL2A_20190206T151259_N0211_R139_T13CEU_20190206T182919.3031.crop.8bit.jp2

15
Antarctica / Re: PIG has calved
« on: February 04, 2019, 05:44:49 PM »
CPOM does an automated version of what you are doing with Sentinel 1 images 6 days apart:
http://www.cpom.ucl.ac.uk/csopr/iv/index.html?glacier_number=3&image_date=190123_190129#output
The most recent pair of 23.1. - 29.1 shows a speed of just over 12m / day, only slightly below your result.

16
Antarctica / Re: Thwaites Glacier Discussion
« on: February 04, 2019, 01:22:54 PM »
I have found some more information on thickness of Thwaites ice tongue, although it does not tell me more because it again is the tongue after separation of B22A (I am guessing this from the shape, no date is given).
It is very low resolution because it comes from a small picture in a slide show type PDF
but it shows that data is around, I am guessing that this comes from the 1km elevation model

17
Antarctica / Re: Thwaites Glacier Discussion
« on: February 03, 2019, 09:38:28 PM »

from an earlier post by ASLR
I found the attached radar soundings which give an idea of the (initial) thickness of B22A. The line RS is along the ice tongue from which B22A broke off a few years before.
source https://www.the-cryosphere.net/11/1283/2017/tc-11-1283-2017.pdf

How much bottom melting has occurred since then is hard to know but we know that it is the deeper water which is melting the glacier and that melting rates become smaller as ice shelves thin towards the seaward end.

Stephan, I think there is slight pivoting of B22A but no westward (i.e. down in the worlview image) movement. But the key point is that it is now clear that it is not held in place by sea ice, since that has now cracked across its width on the landward side.
For comparison the movement since march 2012 when it arrived in its present vicinity https://go.nasa.gov/2HOnreJ as seen on worldview

18
Antarctica / Re: Thwaites Glacier Discussion
« on: February 01, 2019, 06:48:22 PM »
Looking through past years i noticed there has been a swathe of grounded icebergs in the past which seemed to follow the same line as some of the present sea ice.
To have a better comparison I have overlayed an image of 21 feb 2008 in a purple tint over 22 jan 2019
This shows that the stranded icebergs were mostly further west than the curved piece of sea ice. In the same location there are still icebergs which don't move when other bits of ice move around them.
We will probably see soon how much the mobility of the large chunk of sea ice is constrained by frozen in icebergs.

So, my hunch was a bit off, but I thought it might be worth sharing because it tells us something about water depth in that area.

19
Antarctica / Re: Thwaites Glacier Discussion
« on: January 26, 2019, 03:51:16 PM »
Instead of trawling through ASLR's posts over many many pages of the PIG thread which has loads of relevant information I just googled Pelto Thwaites glaicier and hey presto:
https://blogs.agu.org/fromaglaciersperspective/files/2012/10/thwaites-bedrock-2.jpg
which show 3000m /a speeds published in 2001

20
Antarctica / Re: Thwaites Glacier Discussion
« on: January 26, 2019, 03:26:00 PM »
good point, I should have included a scale!
https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=-75.01204475258349&lng=-108.380126953125&zoom=8&preset=1-NATURAL-COLOR&layers=B01,B02,B03&maxcc=52&gain=0.3&gamma=1.3&time=2018-07-01%7C2019-01-10&atmFilter=&showDates=false
shows a 10km bar in the right hand bottom corner which is about as long as the longest red lines
doing this more acurately is a bit pointless because the Sentinel-2 images don't go any further back.
If wipneus could dig out some Landsats....
There are charts with colour coded glacier speed in the PIG thread I think

21
Antarctica / Re: Thwaites Glacier Discussion
« on: January 26, 2019, 02:45:32 PM »
for a more detailed view I have been waiting for a clear image on Sentinel but now I just used the one from 10.1.
This isn't as up to date as the images posted above but I think it shows the stresses of faster glacier movement in the centre and slower movement on both sides.
comparison is between 25.1.2017 and 10.1.2019
orientation is different from worldview!

22
Antarctica / Re: PIG has calved
« on: January 19, 2019, 10:17:28 PM »
Pine Island Bay and Pine  Island Glacier were named after a ship involved in the mapping of this area in 1946. https://en.wikipedia.org/wiki/USS_Pine_Island_(AV-12)
The ship in turn was named after an island off the coast of Florida, a more likely place to find pine trees I guess ;)

23
Arctic sea ice / Re: Arctic Image of the Day
« on: August 29, 2018, 09:13:37 PM »
I find the reaction of a lot of people here bewildering.
I like to think this forum is about facts and science. If I make a statement about the xyz ice shelf I should make sure I know what the xyz iceshelf actually is. I certainly do such fact checking because I would hate to make such a mistake.
It did not take me long to find the information I posted above. Maintaining high standards on this forum is certainly worth the effort in my opinion. (of course there are people who think diferently )
JD  and treform have apologized and that is ok, I hope they take more care in the future. Being incentivized to make the extra effort to reduce the risk of making mistakes is a good thing, right? That is not a personal issue, and should not be about hurt feelings.
Can you really not tell the difference between that and mistake about who said what???

24
Arctic sea ice / Re: Arctic Image of the Day
« on: August 26, 2018, 04:02:24 PM »
comparing the recent image with this one from 2008 shows the ice which is called  "Ward Hunt iceshelf" by the canadian government undisintegrated.
Can you point out where you see an "obliterated ice shelf"?

25
Arctic sea ice / Re: Fram Export
« on: September 25, 2017, 09:02:42 PM »
as a heads up about some interesting research in this area, here is a link to a press release by the AWI
https://www.awi.de/nc/en/about-us/service/press/press-release/arktisches-meereis-erneut-stark-abgeschmolzen.html
Quote
......
During the past weeks, sea-ice thickness measurements were the main topic of the TIFAX (Thick Ice Feeding Arctic Export) campaign, which involved research aircraft using laser scanners and a towed electromagnetic probe. In the area surveyed, which lies to the north of the Fram Strait between Greenland and Svalbard, the sea-ice thickness was ca. 1.7 metres, roughly 50 centimetres more than was recorded in 2016. This is most likely due in part to a higher percentage of several-year-old ice in the area. Nevertheless, the measured thickness is ca. 30 per cent lower than between 2001 and 2004. As Marcel Nicolaus summarises, “Despite the warm winter, the sea ice wasn’t unusually thin. Our explanation is that the small and thin ice coverage from the previous summer – the second-smallest area ever recorded – grew faster and thicker than in other years, since thin ice grows faster than thick ice.”

Pages: [1]