Author Topic: Sea Ice in Amundsen Sea / Pine Island Bay (Read 14433 times)

Stephan · « **on:** September 29, 2019, 05:32:03 PM »

I start this topic to discuss the different patterns of sea ice and its melting during austral summer which should be separated from Thwaites Glacier / Pine Island Glacier calving events (see the individual threads).
I compared the last for years (see attached pictures from EOSDIS Worldview), which differ widely in extent and structure of the sea ice. I chose clear days, so all pictures are from around end September, but not at the same date. In this time of the year the changes from day to day can be relevant.
2016 saw in general a low sea ice cover in that area, 2017 had the closest ice cover. All pictures show the SE→NW flow of the ice.

blumenkraft · « **Reply #1 on:** September 29, 2019, 06:01:29 PM »

My bet is on Circumpolar Deep Water upwellings.

Quote

Glaciological and oceanographic observations coupled with numerical models show that warm Circumpolar Deep Water (CDW) upwelling onto the West Antarctic continental shelf causes melting of the undersides of floating ice shelves. Because these ice shelves buttress glaciers feeding into them, their ocean-induced thinning is driving Antarctic ice-sheet loss today.

Link >> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5510715/

Quote

One day, near the southern edge of Pine Island Glacier Ice Shelf, the researchers directly observed the strength of the melting process as they watched frigid, seawater appear to boil on the surface like a kettle on the stove. To Jacobs, it suggested that deep water, buoyed by added fresh glacial melt, was rising to the surface in a process called upwelling. Jacobs had never witnessed upwelling first hand, but colleagues had described something similar in the fjords of Greenland, where summer runoff and melting glacier fronts can also drive buoyant plumes to the sea surface

Link >> https://www.earth.columbia.edu/articles/view/2815

Quote

The ice, the ocean and the atmosphere are all intrinsically linked, and in Antarctica we now see how complex changes in atmospheric circulation, driven by climate change and the ozone hole, are changing ocean circulation. Increased upwelling of warm, salty Circumpolar Deep Water is melting away the base of the ice shelves and the grounding lines of some of the largest, most vulnerable glaciers and ice streams in Antarctica, resulting in rapid, far-reaching and irreversible changes.

Link >> http://www.antarcticglaciers.org/glaciers-and-climate/ice-ocean-interactions/changes-circumpolar-deep-water/

Stephan · « **Reply #2 on:** November 01, 2019, 06:54:51 PM »

I will add some pictures from time to time to compare 2019 with earlier years.
This year the sea ice seems to be much more fragile than last year. I attach the photos from EOSDIS Oct 30, 2019 (upper) and Oct 30, 2018 (lower). Unfortunately there was no day without clouds, but I think you can get an idea of the difference of this year compared with last year.

PS: The orange circled iceberg is one of the remainders of last year's calving.

Stephan · « **Reply #3 on:** January 11, 2020, 08:43:07 PM »

To bring some more input into this thread I present a picture of the Pine Island Bay (N is to the left) from EOSDIS on Jan 11, 2020. To the lower right you can see the sea ice in front of Thwaites Eastern Ice Shelf, and in the upper right corner you can see the tip of the SW Tributary with its grounded icebergs.
It shows the decomposition of the sea ice NW of Velasco Glacier (circled in green).
I compared the situation with Jan 11 in the last years.
2019 the whole Pine Island Bay was filled with sea ice, so was 2018. 2017, after the big El Niño year the whole Pine Island Bay was free of sea ice, so was 2015. 2016 and 2014 had a mixed appearance. Most part of Pine Island Bay were ice-free, but that NE part of it (the area circled in green and N of it) had an almost complete sea ice cover.

See attached picture.

paolo · « **Reply #4 on:** January 11, 2020, 09:27:43 PM »

Stephan,
what you call "Velasco Glacier" is the NIS. The "Velasco Glacier" bounds the NIS to the north, see picture below.

added zoom

Stephan · « **Reply #5 on:** January 26, 2020, 09:52:08 PM »

Liberation of some sea ice between Thwaites and B-22 iceberg.
In the last month NW of Thwaites Ice Tongue the sea ice opened and fractured into hundreds of floes. They were kept prisoner between the fast ice in the south and the (slowly NW moving) iceberg B-22. With SW winds in the past week some of the ice could escape. Now the wind blows again from the SE. On the western end of that open sea there are a lot of grounded icebergs sitting on an underwater ridge. In addition a bigger iceberg has flown there and got stuck and blocked the flow-out of the sea ice. I have called it "Cork". Now a bigger part of it has calved and after that it turned counterclockwise (40°) to give way to the sea ice which is now slowly flowing out.

The first image shows the area I am writing about. Green circled is the open water with the sea ice on it. The orange square is the region of the "Cork" and the area of the second image.
The second image gives the details. All grounded icebergs are circled in yellow. So it is not easy for an ordinary sea ice floe to move around these obstacles...

Stephan · « **Reply #6 on:** February 28, 2020, 10:14:54 PM »

The freezing season has started in Southern Amundsen Sea.
As a follow-up to my last posting in this thread I must consider that most of the icebergs in the green circled area could not leave the open seas south of B-22. The cork has further turned counterclockwise and closed the gap almost completely. This movement was partly made possible by the further NW movement of B-22 (ca. 2 km in the last five weeks).
Three weeks ago the whole green circled area contained open waters with some icebergs. Now it has rapidly frozen. So I do not expect any further erosion of the fast ice south of it (as was observed massively last year). This will also support the ice west of the Thwaites Ice Tongue and Crosson Ice Shelf for the next months.

See attached picture.

Stephan · « **Reply #7 on:** December 20, 2021, 09:42:28 PM »

I had a look at the situation of sea ice along Pine Island Bay and came across to make a picture of each year since 2016 for a qualitative comparison.
All pictures come from around Dec 15-Dec 23, trying to find a real clear day isn't too easy.
What I find: 2016 had extraordinary low sea ice in that area, followed by 2018, 2019 and 2020. 2021 is among the years with the highest sea ice concentration, together with 2017. The distribution changes from year to year. Sometimes B-22 is surrounded by open waters and Pine Island Bay is full of ice, in other years it is the other way round.
I guess that sea ice stabilizes PIG, Thwaites and B-22 - so let's hope 2021 (soon 2022) will be on the "higher ice side" in this Austral summer.

See attached picture. I added some features and names for a better orientation. North is almost left.

Stephan · « **Reply #8 on:** December 24, 2022, 10:29:37 PM »

Fast sea ice loss between Dec 20 and Dec 24 of 627 km², between east of TEIS and the ice shelf to the east coast of Pine Island Bay. And it seems there is more to come...
https://worldview.earthdata.nasa.gov/?v=-1713316.8569378846,-438069.33890070784,-1522724.8569378846,-342709.33890070784&p=antarctic&l=Coastlines_15m,VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor&lg=false&l1=Coastlines_15m,VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor&lg1=false&ca=false&cv=59&t=2022-12-20-T17%3A29%3A13Z&t1=2022-12-24-T17%3A29%3A13Z

baking · « **Reply #9 on:** December 25, 2022, 05:24:40 AM »

Not sure if this is the best place for it, but when I was looking at Stephen's Worldview comparison, I noticed that a lot of the "fast" ice off of the eastern front Thwaites Eastern Ice Shelf seemed to have shifted slightly. Confirming with today's lo-res 12-day GIF from Sentinel-1 shows a lot more of the ice has broken up, but just not floated away yet. It's going to be an interesting Summer.

FredBear · « **Reply #10 on:** December 25, 2022, 09:52:11 AM »

If you move Stephan's image from his Reply 8 up so that you can see the barrier of grounded icebergs below B22 you can see "leakage" through the barrier.
All the rattling around by the various icebergs must have rubbed some of the high points of the seabed and low points of the icebergs.

Stephan · « **Reply #11 on:** December 30, 2022, 08:35:03 PM »

Another large portion of fast ice in Pine Island Bay is on the move.
An area of roughly 900 km² east of Thwaites Eastern Ice Shelf (TEIS) has started to erode (left/above of the dotted orange line in the picture). Will this event have an impact on TEIS itself?
Picture is ca. 85*70 km, N is left, a little down.

baking · « **Reply #12 on:** December 31, 2022, 05:57:03 AM »

Quote from: Stephan on December 30, 2022, 08:35:03 PM

An area of roughly 900 km² east of Thwaites Eastern Ice Shelf (TEIS) has started to erode

Nice catch. I swear it happened since I last looked a few hours ago. Cracks in the sea ice now reach to the Eastern flank of the TEIS. It's been many years since that was last exposed to open water. I'm going to have to do some digging to put a number on it.

Edit: Middle of 2017, so over 5 years. See this long-term GIF: https://twitter.com/kevpluck/status/1228472054430781440

baking · « **Reply #13 on:** December 31, 2022, 03:58:45 PM »

Here is a 2-day GIF made from radar images to highlight recent changes to the sea ice and icebergs off of the Eastern flank of Thwaites Eastern Ice Shelf (TEIS.) Alignment is not perfect because these are from different orbits. Image size is 48x56 km.

baking · « **Reply #14 on:** January 02, 2023, 03:23:57 PM »

Here is an updated 4-day GIF of the sea ice off of the Eastern flank of TEIS.

Stephan · « **Reply #15 on:** January 04, 2023, 08:30:09 PM »

New massive erosion of fast ice in Pine Island Bay.
According to EOSDIS an area of roughly 410 km² of fast ice eroded yesterday (dotted orange line), following the latest erosion along the eastern flank of TEIS (dotted yellow line). The new erosion goes almost all along Pine Island Bay to its eastern shore.

See attached picture. N is left, a little down. Size of the image is around 115*85 km.

baking · « **Reply #16 on:** January 05, 2023, 08:13:08 AM »

The largest iceberg in Pine Island Bay became free in yesterday's sea ice breakup. 12-day GIF, 56 KM on a side.

paolo · « **Reply #17 on:** January 17, 2023, 11:12:58 PM »

I am posting three animations related to Pine Island Bay: Pine Island Glacier sector, Thwaites Glacier sector and Crosson Ice Shelf sector (Sentinel1 low resolution images from 01/10/2022 to 17/01/2023).
Sea ice disintegration, which in itself has no influence on glaciers and ice shelves (which is also true for sea surface temperature), but it leaves the ice mixtures and icebergs in front of them undefended and free to move away, which leaves the fronts of glaciers and ice shelves undefended with the possibility of new calving.
Short and scattered animations have already been published, but it seemed important to me to present longer and more complete animations.
Given the volume of the three animations there will be three separate posts.

Pine Island Glacier sector:
Regardless of the sea ice: the two polynias in front of the PIG have reappeared (especially the southern one) and the effects of their presence are evident.

Click to animate and click again to enlarge completely

paolo · « **Reply #18 on:** January 17, 2023, 11:17:50 PM »

Thwaites Glacier area:

Click to animate and click again to enlarge fully

paolo · « **Reply #19 on:** January 17, 2023, 11:19:23 PM »

Crosson Ice Shelf area :

Click to animate and click again to enlarge completely

Stephan · « **Reply #20 on:** January 19, 2023, 09:14:45 PM »

Thank you paolo for these animations. It is very interesting to see the movement of beforehand immobilized icebergs in sea ice after the sea ice has drifted away.
Maybe you add the colour codes of the shelf boundaries to one of your posts - thank you.

baking · « **Reply #21 on:** January 22, 2023, 06:02:32 PM »

12-day GIF of critical fast ice breaking up off of Thwaites and Crosson. Icebergs in center-left of image are grounded, as are icebergs in lower right. Icebergs in upper-right are not grounded (as can be seen in paolo's GIF two posts above.)

Fast ice is anchored by grounded icebergs and if it loses that connection it can become unstable.

baking · « **Reply #22 on:** January 23, 2023, 10:11:53 PM »

Check out the sea ice off of the Eastern front of Thwaites in today's Worldview Images. Comparison if from 4 days ago.

https://worldview.earthdata.nasa.gov/?v=-1706807.527173194,-469930.77781300945,-1510199.527173194,-378922.77781300945&p=antarctic&l1=Reference_Labels_15m(hidden),Reference_Features_15m(hidden),Coastlines_15m,VIIRS_NOAA20_CorrectedReflectance_TrueColor(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor&ca=true&cv=27&t=2023-01-19-T07%3A02%3A47Z&t1=2023-01-23-T01%3A02%3A47Z

grixm · « **Reply #23 on:** January 24, 2023, 08:50:55 AM »

Quote from: baking on January 22, 2023, 06:02:32 PM

12-day GIF of critical fast ice breaking up off of Thwaites and Crosson. Icebergs in center-left of image are grounded, as are icebergs in lower right. Icebergs in upper-right are not grounded (as can be seen in paolo's GIF two posts above.)

Fast ice is anchored by grounded icebergs and if it loses that connection it can become unstable.

One down

baking · « **Reply #24 on:** January 24, 2023, 03:48:46 PM »

Here is a 12-day GIF of the sea ice off the Eastern flank of Thwaites Eastern Ice Shelf (TEIS) which confirms what I saw through the clouds on Worldview yesterday. Image is 50km on a side.

grixm · « **Reply #25 on:** January 25, 2023, 09:46:33 PM »

A bit chunk of the Thwaites fast ice and melange is going

Chris83 · « **Reply #26 on:** January 28, 2023, 06:41:30 PM »

Sea ice along the coast is imploding
Is it the sun? is it the open water ?
Massive change in 24 hours.

vox_mundi · « **Reply #27 on:** January 28, 2023, 07:11:50 PM »

Quote from: Chris83 on January 28, 2023, 06:41:30 PM

Sea ice along the coast is imploding
Is it the sun? is it the open water ?
Massive change in 24 hours.

Yes, both

Off shore wind probably causing upwelling directed away from coast

oren · « **Reply #28 on:** January 28, 2023, 07:33:07 PM »

Please post here all discussions pertaining to sea ice in front of PIG and Thwaites glaciers, including fast ice.
Discussions of calving, glacial tongues, ice shelves and escape of small and large icebergs from the directly adjacent area go in the respective glacier threads.
Icebergs that are already calved and not directly adjacent to the tongues/shelves (e.g. B-22A, B-29) are to be discussed in the Antarctic Icebergs thread.
Sometimes the demarcation is a bit obscure as satellite images often contain all three subjects, but judge it by the content of your accompanying text and you will rarely be wrong.

Stephan · « **Reply #29 on:** January 28, 2023, 07:39:35 PM »

Quote from: Chris83 on January 28, 2023, 06:41:30 PM

Sea ice along the coast is imploding
[...]
Massive change in 24 hours.

Thank you for spotting this. I was just about to post it. Around 1,000 km² of ice is affected.
It looks like a rapid and complete breakdown of the fast ice in front of PIIS, possibly later on with impacts on PIIS.
Another big breakup in fast ice in front of Crosson Ice Shelf (separate post).

Stephan · « **Reply #30 on:** January 28, 2023, 07:51:10 PM »

(A little difficult to place this post into the right thread, as we have a Crosson&Dotson, an iceberg and a sea ice Amundsen/Pine Island thread). I have announced this post some minutes ago in this thread, so I stay with it.

Parallel to the collapse of fast ice in Pine Island Bay and several erosion phenomena along TEIS and Thwaites itself a new, around 60 km long rift has developed overnight in the fast ice in front of Crosson Ice Shelf.
If it drifts away, iceberg B-45 will freely move, probably directly towards the line of grounded icebergs S of B-22.

See attached picture. N is left, a little down, size is ca. 120*85 km.

FredBear · « **Reply #31 on:** January 28, 2023, 08:50:33 PM »

When I posted at 03.30pm (and amendments 30 mins. later) on the icebergs thread it was based on the initial Worldview image. The subsequent updated image shows much more and clearer breakup in all areas.

I think that katabatic winds from the continent might be a good explanation for the current level of damage to the fast ice, together with the lack of clouds in the area?

Although there may be most of a month before the minimum ice extent and area numbers are reached, in the southern extremities of the seas ice formation starts early in February (and may already be building in the Weddell Sea where it is blocked in by pack ice??)

baking · « **Reply #32 on:** January 29, 2023, 10:25:31 AM »

I hate to mess with Oren's plan, but as of today's this might be the last fast ice in the Amundsen Sea, at least for this season. 12-day GIF. Icebergs in lower left corner are grounded, anchoring this last piece, at least for now. Image is 54 x 30 km.

Chris83 · « **Reply #33 on:** January 29, 2023, 12:51:35 PM »

In less than 5 days, the sea ice along the coast has imploded everywhere
New Polarview 29.01.2023

Stephan · « **Reply #34 on:** January 29, 2023, 03:47:40 PM »

A "quick and dirty" measurement in EOSDIS gave an area of 3,100 km² of fast ice in Pine Island Bay that has fallen apart in the last two days.

Stephan · « **Reply #35 on:** January 29, 2023, 04:14:00 PM »

Quote from: Stephan on January 28, 2023, 07:51:10 PM

Parallel to the collapse of fast ice in Pine Island Bay and several erosion phenomena along TEIS and Thwaites itself a new, around 60 km long rift has developed overnight in the fast ice in front of Crosson Ice Shelf.
If it drifts away, iceberg B-45 will freely move, probably directly towards the line of grounded icebergs S of B-22.

The whole marked area (670 km²) today has left the fast ice in front of Crosson Ice Shelf today.

Chris83 · « **Reply #36 on:** January 29, 2023, 07:15:24 PM »

uniquorn · « **Reply #37 on:** January 29, 2023, 07:52:57 PM »

awi sic-leads jan1-28

Chris83 · « **Reply #38 on:** January 29, 2023, 08:41:34 PM »

Worldview with another perfect day over the area.
New cracks are appearing everywhere
Quite strong wind coming from land (25 mph /Ventusky) , but cold (-7/-9c)

Stephan · « **Reply #39 on:** January 30, 2023, 07:38:18 PM »

Another portion of fast ice in front of Thwaites Ice Tongue has "calved". Today an area of 315 km² is affecred (dotted orange line and orange arrow). The question arises: How far into Thwaites Ice Tongue will this breakup happen this austral summer?
Cork looks like it's grounded.
Further east (up in the picture) a line of icebergs are grounded along the tip of Thwaites Eastern Ice Shelf (TEIS) into NE direction, circled in light blue. It has developed a barrier for the ice mélange east of TEIS which originated in the collapse of sea ice and isolated icebergs in that sea ice in Pine Island Bay (yellow arrow).

See attached picture. N is left, a little down, its size comprises an area of 150*115 km.

Chris83 · « **Reply #40 on:** January 31, 2023, 06:56:59 PM »

Another great clear day in the area...Perfect for Worldview.
31.01.2023
Seems B22 is speeding up (IMO)

Chris83 · « **Reply #41 on:** February 02, 2023, 07:40:00 PM »

Your Worldview update
02.02.2023
Another perfect view with no clouds
#B22 running away

baking · « **Reply #42 on:** February 03, 2023, 04:28:05 PM »

5-day GIF of the last bit of fast sea ice remaining in the Amundsen Sea. Icebergs in lower left are grounded.

Espen · « **Reply #43 on:** February 05, 2023, 11:10:14 AM »

Pine Island Glacier - Feb. 3 - Feb. 5 2023:

Please click on image to enlarge!

oren · « **Reply #44 on:** February 05, 2023, 11:45:15 AM »

The above post moved here as it is more general to the whole Amundsen Sea rather than PIG itself.
Quite a few changes seen. I note B-22A is dragging with it parts of the outer ice field, including some small stuck icebergs.
And some more icebergs in front of Thwaites dragged away by the incessant outward movement of the sea ice.

baking · « **Reply #45 on:** February 08, 2023, 04:41:22 PM »

5-day GIF of the remaining fast ice. Four of the original icebergs remain attached to the ice in the lower left, but only one or two appear grounded.

baking · « **Reply #46 on:** February 09, 2023, 08:15:40 PM »

12-day high resolution GIF of the last remaining fast ice. Looks like only one grounded iceberg is still connected (not going to say anchored) to the fast ice.

baking · « **Reply #47 on:** February 10, 2023, 05:43:00 PM »

No Polarview today, but this 1-day GIF from Worldview shows some calving from the "underside" (Western flank) of the remaining fast ice.

baking · « **Reply #48 on:** February 10, 2023, 10:10:47 PM »

Better images from later in the day today show major cracks in the fast ice (center left of this image.)

baking · « **Reply #49 on:** February 13, 2023, 01:01:43 PM »

Here's a 12-day GIF of what's left of the fast ice. No longer connected to the grounded icebergs in the lower left, but there may be three grounded icebergs in the lower left. But they are far from Thwaites so I don't know if they can help much.

News:

Author Topic: Sea Ice in Amundsen Sea / Pine Island Bay (Read 14433 times)

blumenkraft