Author Topic: Pine Island Glacier (PIG) Calving and Discussion (Read 742168 times)

gerontocrat · « **Reply #900 on:** January 20, 2019, 05:53:00 PM »

Quote from: Stephan on January 20, 2019, 04:49:37 PM

I found this one here from 1955:
http://data.pgc.umn.edu/maps/antarctica/navoceano/01/preview/Amundsen%20Sea%20to%20Palmer%20Peninsula.jpg

Ask and Stephan provides.

of course, then I ask if today's map can be superimposed to see the change. What a cheek!

Stephan · « **Reply #901 on:** January 20, 2019, 08:16:49 PM »

This map here has a different orientation (N to the (lower) left) and does not cover exactly the same area but it says it is from 2018:
http://data.pgc.umn.edu/maps/antarctica/pgc/17/preview/Map%2011%20Amundsen%20Sea%20Ed%203.jpg

Stephan · « **Reply #902 on:** January 20, 2019, 08:22:00 PM »

Quote from: Stephan on January 19, 2019, 08:56:22 PM

Also at the NE edge of Pine Island Bay a massive disintegration of the fast ice occurred last week. See the new cracks (marked in red) and the little island (is that Pine Island?) at the bottom (marked in green), now freed from ice. Please be aware that these two pictures show the changes that happened last week (upper pic Jan 12, lower pic Jan 19)
Taken from EOSDIS worldview

According to the map just linked the little island(s) now ice-free are named Clark Islands.

crandles · « **Reply #903 on:** January 20, 2019, 09:14:45 PM »

Not sure I would trust me if I were to try tracing the line. Not sure if that ice front date is 1907, 1927 or 1937. Ice front perhaps is similar to 1972-2016. 2018 moved more, however bay seems to have widened??

SteveMDFP · « **Reply #904 on:** January 20, 2019, 11:05:25 PM »

Quote from: Stephan on January 20, 2019, 01:08:22 PM

Even with a 9-day difference in the "Start comparison" mode in EOSDIS worldview you see a movement of the PIG. I have looked at other places in Antarctica by this method but haven't found any "as speedy as PIG" glacier or ice shelf. Only the fast ice along the Thwaites Ice tongue comes close to that.

Nomenclature can be confusing. Fast ice doesn't move at all--it's stuck fast to the land.

FredBear · « **Reply #905 on:** January 20, 2019, 11:41:24 PM »

More breakage from PIG - SE corner under haze (top left, glacier front) between 19 & 20th Jan?
1st pic. 19/01, 2nd 20/01
+ movement NW of Thwaites (just below images - sorry!)

b_lumenkraft · « **Reply #906 on:** January 21, 2019, 07:43:19 AM »

Degradation as a Gif.

Stephan · « **Reply #907 on:** January 21, 2019, 06:25:46 PM »

Thanks.
And a 'like' earned!

b_lumenkraft · « **Reply #908 on:** January 21, 2019, 06:40:15 PM »

Thank you Stephan!

Stephan · « **Reply #909 on:** January 21, 2019, 07:59:14 PM »

It is obvious how the remains of the calvings in front of the PIIS have accelerated as soon as the fast ice broke up. I didn't expect that sea ice alone would have such an immense buttressing effect.
I wonder what will happen next with the PIIS front and the SW tributary which are now exposed to sea water without any ice cover...

oren · « **Reply #910 on:** January 21, 2019, 10:26:20 PM »

It does not have to be an effect of the sea ice, but quite possibly a common effect of a strong northward wind/current that both cleared the sea ice and the calving remains. If that's the case, I would guess the same factor is also pulling at the ice front, tearing away any loose pieces and slightly increasing chances of further calving.

Stephan · « **Reply #911 on:** January 22, 2019, 08:01:39 PM »

A small part in the northeasternmost corner of the PIIS has calved these days. I circled the resulting iceberg and the corner where it broke off.
See attached picture.

oren · « **Reply #912 on:** January 22, 2019, 10:13:06 PM »

I want to thank the several people posting frequent updates, images and animations in this thread. I won't list names for fear of forgetting someone, but you know who you are. Recently it's been very active and interesting, as befits "ground zero" of SLR in Antarctica (along with neighboring Thwaites).

Steven · « **Reply #913 on:** January 26, 2019, 05:56:57 PM »

Pine Island Glacier: 18 months of flow and calving
https://adrianluckman.wordpress.com/2019/01/25/

b_lumenkraft · « **Reply #914 on:** January 26, 2019, 06:10:48 PM »

Cool! Great find.

Stephan · « **Reply #915 on:** January 26, 2019, 08:26:45 PM »

Steven: Absolutely brilliant. I kindly ask you to update that animation to provide us with the dynamics of this "most actve" Antarctican glacier.

Stephan · « **Reply #916 on:** January 26, 2019, 08:34:14 PM »

Quote from: Stephan on January 22, 2019, 08:01:39 PM

A small part in the northeasternmost corner of the PIIS has calved these days. I circled the resulting iceberg and the corner where it broke off.
See attached picture.

Here are two detailed pictures before and after this little calving event from Sentinel on Jan 01 and Jan 21. The frame size is around 18 x 10 km.

Stephan · « **Reply #917 on:** January 26, 2019, 09:24:33 PM »

I scanned the PIIS for any cracks and I've found two of them, probably both were already mentioned in this thread. It was a little bit tricky to draw the green line along the cracks on the image but I tried to reproduce their position as exactly as possible. Unfortunately no Sentinel picture was completely cloudless, and Dec and earlier photographs weren't useable for a crack detection, probably due to too much snow on the glacier (or the cracks haven't been there at that time!). We should follow their position, width and length to be prepared for another major calving event in 2019. The distance of the "southeastern crack" from the calving front is approx. 10-12 km.

Steven · « **Reply #918 on:** January 26, 2019, 10:10:52 PM »

Quote from: Stephan on January 26, 2019, 08:26:45 PM

I kindly ask you to update that animation

That animation was made by Adrian Luckman. I had posted a link to his blog:

https://adrianluckman.wordpress.com/

wdmn · « **Reply #919 on:** January 27, 2019, 12:20:46 AM »

Quote from: Stephan on January 26, 2019, 09:24:33 PM

I scanned the PIIS for any cracks and I've found two of them, probably both were already mentioned in this thread. It was a little bit tricky to draw the green line along the cracks on the image but I tried to reproduce their position as exactly as possible. Unfortunately no Sentinel picture was completely cloudless, and Dec and earlier photographs weren't useable for a crack detection, probably due to too much snow on the glacier (or the cracks haven't been there at that time!). We should follow their position, width and length to be prepared for another major calving event in 2019. The distance of the "southeastern crack" from the calving front is approx. 10-12 km.

The shorter crack in your image already appears to be quite wide by the last frame (which is Jan. 23) of the animation by Adrian Luckman posted above.

FredBear · « **Reply #920 on:** January 27, 2019, 07:18:04 PM »

SW corner breaking beyond end of small crack - larger ice being propelled by finer debris (as was SE corner last time). Need cloud-free pics to see main crack, more to come this season? Some clockwise circulation near face of glacier, increasing finer debris but area not clearing much.

Edge of fast ice still slowly degrading around Thwaites and its old 'berg.

Stephan · « **Reply #921 on:** January 27, 2019, 08:43:53 PM »

Thank you for that information. I have just checked with the latest Sentinal image from Jan 21. I guess it is the area west of the shorter crack I mentioned above which looked already kind of scattered. I circled the "suspicious" area in orange. NE to it the aforementioned crack in yellowish green. A crack I didn't mention in my yesterday's post is visible at the outlet of the SW tributary glacier. It has a length of around 1200 m and has been there for many weeks. I marked it in a red circle. With the "naked" front of this glacier, combined with today's minor calving event and no support or buttressing in any way, a calving also of this glacier is i.m.o. likely this year.
Before I finish: SE to that mess there is an area which seems to contain various icebergs in a frozen sea. I marked that area in blue and this area goes beyond that frame which has a size of around 12,5 x 25 km.
See attached picture.

b_lumenkraft · « **Reply #922 on:** January 28, 2019, 05:28:29 AM »

Wait, how can that be icebergs.

oren · « **Reply #923 on:** January 28, 2019, 06:16:31 AM »

If I understand the orientation correctly, it's probably some ice rise. These glaciers are hard to wrap your head around.

FredBear · « **Reply #924 on:** January 28, 2019, 10:12:24 AM »

The last posted Sentinal image pre-dates the last calving (estimated in orange area) and PIG is from right. My images (reply 920) are screen shots from arctic.io. and show the newly exposed end of the crack shown in yellow. The area circled in blue is the edge of the glacier, both sides of which tend to look broken and dark, break up irregularly and on the last two occasions have produced a "puff" of smaller ice behind the main 'bergs.

Perhaps interestingly, the big calvings used to have lost connection at the edges first, now major 'bergs split from the glacier without that preparation. (reply 913, video from adrianluckman), but the back pressure from the SW tributary has also gone as the calving advances upstream.

Stephan · « **Reply #925 on:** January 28, 2019, 05:47:26 PM »

Quote from: oren on January 28, 2019, 06:16:31 AM

If I understand the orientation correctly, it's probably some ice rise. These glaciers are hard to wrap your head around.

Does the fact that there is an "ice rise" principally exclude the presence of frozen sea water with ice bergs in it above that ice rise? I am no glaciologist, so please excuse my question.

crandles · « **Reply #926 on:** January 28, 2019, 06:00:36 PM »

Quote from: Stephan on January 28, 2019, 05:47:26 PM

Quote from: oren on January 28, 2019, 06:16:31 AM
If I understand the orientation correctly, it's probably some ice rise. These glaciers are hard to wrap your head around.
Does the fact that there is an "ice rise" principally exclude the presence of frozen sea water with ice bergs in it above that ice rise? I am no glaciologist, so please excuse my question.

If the glacier has retreated back further than ever previously known and the glacier is moving forward, then surely the ice almost certainly originated from snow further inland?

This location certainly looks like

Quote

the edge of the glacier, both sides of which tend to look broken and dark, break up irregularly

to me as FredBear said.

Stephan · « **Reply #927 on:** January 28, 2019, 06:40:08 PM »

I hope I understand that correctly. The ice bergs in that region of course originate from PIG. But couldn't the "gaps" between them be already open sea, covered with (thinner) sea ice??

Andreas T · « **Reply #928 on:** January 28, 2019, 07:24:07 PM »

Looking at the coastline marked on worldview, suggests that bedrock is below the waterline in this area. I think the ice is floating at that point so when ever a crack opens it fills with seawater and possibly meltwater from below. You see dark areas where cracks open in Luckman's animation. Information where the grounding line is for the ice is probably further up the thread.

FredBear · « **Reply #929 on:** January 28, 2019, 09:51:22 PM »

Thoughts of an "ice-rise" just complicates the picture - the edges of the PIG move more slowly than the centre and have large cracks where they are stressed, which probably produces the smaller ice debris too.
The major cracks across the centre of the glacier are often covered by drifting snow and are only revealed as the snow ablates or the cracks widen . . . and calved icebergs break up in ways that demonstrate more weaknesses that had remained hidden.

Stephan · « **Reply #930 on:** February 01, 2019, 05:10:59 PM »

A day of complete cloudlessness on Jan 31 allowed a clear Sentinel picture on the PIIS. I checked the cracks and I detected three of them. In yellowish green there is the crack (actually it is two cracks not yet connected together in the centre) I reported about some days ago. It looks quite new with sharp edges. In brown there is another crack which looks much older and which is filled with snow. This is probably the crack wipneus and ASLR mentioned some months ago. The third crack in pale magenta is the one close to the calving front. It has not changed in width and length since last week, but due to the rapid movement (has anyone a number of the speed of PIIS at hand?) it has changed its absolute position.
See attached picture.

Stephan · « **Reply #931 on:** February 01, 2019, 06:27:31 PM »

This has been posted before in the Thwaites Glacier thread - Neven, could you remove this posting into the right thread? Thanks.

Susan Anderson · « **Reply #932 on:** February 01, 2019, 07:25:31 PM »

Sorry Stephan. I've removed it, should have been more careful. Of course!

Stephan · « **Reply #933 on:** February 01, 2019, 07:36:47 PM »

No problem, you're welcome

bairgon · « **Reply #934 on:** February 04, 2019, 01:26:09 PM »

Quote from: Steven on January 26, 2019, 05:56:57 PM

Pine Island Glacier: 18 months of flow and calving
https://adrianluckman.wordpress.com/2019/01/25/

My best estimate of flow rate from this video, picking a feature and seeing how far it moved on my screen vs the scale is that flow is 4.5 km per year, which exceeds recently reported flow rates of "up to 4000m per year" e.g. http://www.antarcticglaciers.org/glaciers-and-climate/shrinking-ice-shelves/pine-island-glacier/

Since the recent calving there is visible movement on Worldview in a month. Using Sentinel, comparing the images from 28/12/2018 and 31/01/2019 it appears the rate is around 4.6 km per year (430m in 34 days). So it is maintaining the faster rate.

Resolution on Worldview is too low to be accurate.

Andreas T · « **Reply #935 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.

Stephan · « **Reply #936 on:** February 04, 2019, 08:28:00 PM »

So it seems, as expected, again an increase of speed of this fastest glacier in Antarctica. Higher speed also means thinning, stretching and a more likely formation of cracks and crevasses. This is what I heard from scientists in various youtube videos. Together with the missing ice at the junction of PIIS and the SW tributary and no sea ice at the calving front a bigger calving event is likely again - probably resulting in a higher than ever calving front.
I am not a glaciologist, so please correct me if I am wrong...

PS Is there any update of the position of the grounding line of PIG?

bairgon · « **Reply #937 on:** February 04, 2019, 08:56:57 PM »

Quote from: Andreas T 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:

Ah, that's a great resource. And indeed the flow rate from the first analysis is lower than the average, and the rate from the latest analysis is greater than the average. The change is only about 9% - 11 m/day to 12 m/day - but that is in just over 3 years.

oren · « **Reply #938 on:** February 05, 2019, 03:09:59 AM »

Thanks for the CPOM link.
Watching the animation, the PIG certainly seems to be consistently accelerating.

Stephan · « **Reply #939 on:** February 06, 2019, 10:05:00 PM »

Minor calving at the SW end of the PIIS, an area already designed to calve because of many cracks with the approx. size of 3 x 0,5 km has calved this week.
See attached picture.

Stephan · « **Reply #940 on:** February 06, 2019, 10:12:45 PM »

Minor break-up of fast sea ice on the NE shore of Pine Island bay. Total are is about 15 x 2-3 km². Mostly it is young thin ice, but two packs derived from the ice shelf (marked in blue) have also disintegrated. In addition new and older cracks in that shelf are marked in orange. Probably future breaks, possibly this austral summer?
See attached figure.

FredBear · « **Reply #941 on:** February 07, 2019, 12:49:09 AM »

. . and another spray of ice from the SE corner of the glacier front on 2019-02-06 . . (top left of image)

bairgon · « **Reply #942 on:** February 07, 2019, 09:17:12 AM »

Quote from: FredBear on February 07, 2019, 12:49:09 AM

. . and another spray of ice from the SE corner of the glacier front on 2019-02-06 . . (top left of image)

That appears to be a new calving with some bergs, but a lot of brash ice. See https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=-74.93585300426079&lng=-100.777587890625&zoom=10&preset=CUSTOM&layers=B01,B02,B03&maxcc=76&gain=1.0&gamma=1.0&time=2018-08-01%7C2019-02-06&atmFilter=&showDates=false&evalscript=cmV0dXJuIFtCOEEqMSxCMDMqMSxCMDIqMV0%3D

Edit: Checking that URL shows an image for 6th Feb and I can't seem to get to 7th of Feb now. But I definitely saw it earlier today - as per the screen shot below.

Stephan · « **Reply #943 on:** February 07, 2019, 05:49:51 PM »

Please compare this picture with my reply #916. The cracks were already visible at that time. I checked their length and width on Sentinel on Feb 06 with mid-January photos and they didn't change. So for a sudden calving cracks do not necessarily need to widen and lengthen beforehand...

Stephan · « **Reply #944 on:** February 07, 2019, 06:42:23 PM »

A new crack has developed in the last two weeks on one of the icebergs at the western flank of PIIS. It has a length of roughly 1.2 km and almost reached the eastern side of this iceberg.
See attached figure, crack marked in yellowish green.
I wonder what happens when the calving front reaches this area of already broken-up ice at the western flank of PIIS. Will this accelerate the degradation in general and lead to more little calving events?

Stephan · « **Reply #945 on:** February 11, 2019, 08:54:49 PM »

"Clean Up" of fast sea ice in Pine Island Bay.
All red marked areas have lost fast sea ice in the last week/during the last weekend.
The areas are marked in red at the PIIS show minor calvings (see more details above in this thread). The blue marked iceberg is grounded and is located at the same place for quite a while now. I tried to indicate some names of islands and glaciers for a better orientation. The whole area contains ca. 320 x 175 km, so it is huge.
See attached graph

PS: In Sentinel some of the edges close to the slow, not really moving ice shelves show the first re-freezing.

FredBear · « **Reply #946 on:** February 12, 2019, 11:51:27 AM »

The Sentinel images are brilliant (Reply 642) and if you use the forward and back arrows at the top it is so easy to see how things are changing.
I usually use the arctic.io views which are showing that the large floes outside PIG/Thwaites have been cracking up (2019-02-11) like the ice surrounding B22A. (arctic.io is daily but smaller scale and clouds obscure some details).

Stephan · « **Reply #947 on:** February 12, 2019, 08:13:03 PM »

The "clean up" of the fast ice in Pine Island Bay continues even faster. Today a ca. 350km² area in the northeastern part of the Bay was cleared from ice, in addition a lot of the northeastern coast. Also the SW side of the bay lost further fast sea ice. All these areas are marked in red. The big yellowish green marked feature in the center is the biggest remaining iceberg from the calving event in October 2018. Some of the freshly eroded fast ice was pushed against the eastern margin of the Thwaites Ice Tongue (marked in blue).
See attached picture.

Stephan · « **Reply #948 on:** February 15, 2019, 08:25:37 PM »

The erosion of the fast sea ice along the NE coast of Pine Island Bay continues. Large areas have lost their sea ice due to strong E / SE winds. It is too cloudy to post a picture here, but I put in the link of EOSDIS comparison of today with Feb 11: https://worldview.earthdata.nasa.gov/?ca=false&cm=swipe&cv=51&p=antarctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Coastlines&l1=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Coastlines&t=2019-02-15-T00%3A00%3A00Z&z=3&t1=2019-02-11-T00%3A00%3A00Z&v=-1839104.0000000005,-481855.99999999994,-1505280.0000000005,-303423.99999999994

bairgon · « **Reply #949 on:** February 16, 2019, 02:45:55 PM »

Quote from: Stephan on February 11, 2019, 08:54:49 PM

The blue marked iceberg is grounded and is located at the same place for quite a while now.

That is now on its way. See below.

News:

Author Topic: Pine Island Glacier (PIG) Calving and Discussion (Read 742168 times)

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