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AbruptSLR

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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #150 on: September 29, 2015, 09:08:57 PM »
The linked article discusses a pay-walled report entitled: "A Strategic Vision for NSF Investments in Antarctic and Southern Ocean Research (2015)" that prioritizes science in Antarctica:

http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=21741


Extract: "Melting Ice Sheets, Genomic Studies, and Deep-Space Observations Are Top Priorities for Next Decade of Antarctic and Southern Ocean Research
 
WASHINGTON -- An initiative to better understand how melting ice sheets will contribute to sea-level rise, efforts to decode the genomes of organisms to understand evolutionary adaptations, and a next-generation cosmic microwave background experiment to address fundamental questions about the origin of the universe are the top research goals for Antarctic and Southern Ocean science recommended in a new report from the National Academies of Sciences, Engineering, and Medicine.
 
The report, which offers a strategic vision to guide the U.S. Antarctic Program at the National Science Foundation over the next 10 years, also recommends that NSF continue to support a core program of investigator-driven research across a broad range of disciplines and strengthen logistic and infrastructure support for the priority research areas.
 
“The discoveries emerging from the Antarctic and the Southern Ocean advance our understanding of how our planet works and how our universe formed,” said Robin Bell, professor of geology and geophysics at the Lamont-Doherty Earth Observatory of Columbia University in New York and co-chair of the committee that conducted the study.  “Continued Antarctic and Southern Ocean research will produce new insights that will be critical as society adapts to the global consequences of change in these remote regions.”
Informed by extensive input from the scientific community, the committee selected the three large-scale research goals based on the criteria of compelling science, potential for societal impact, time sensitivity, readiness and feasibility, and key areas for U.S. and NSF leadership.  Additional criteria included partnership opportunities, impacts on NSF program balance, and the potential to help bridge disciplinary divides.
 
The report proposes a major new effort called the Changing Antarctic Ice Sheets Initiative to investigate how much and how fast melting ice sheets will contribute to sea-level rise.  The initiative’s components include a multidisciplinary campaign to study the complex interactions among ice, ocean, atmosphere, and climate in key zones of the West Antarctic Ice Sheet, and a new generation of ice core and marine sediment core studies to better understand past episodes of rapid ice sheet collapse."
A second strategic research priority is to understand from a genetic standpoint how life adapts to the extreme Antarctic environment.  For more than 30 million years, isolated Antarctic ecosystems have evolved to adapt to freezing conditions and dramatic environmental changes, and now must adapt to contemporary pressures such as climate change, ocean acidification, invasive species, and commercial fishing.  Sequencing the genomes and transcriptomes of critical populations, ranging from microbes to marine mammals, would reveal the magnitude of their genetic diversity and capacity to adapt to change. 
 
In addition to being a vast natural laboratory, Antarctica has a dry, stable atmosphere that offers an ideal setting for astrophysical observations.  The report recommends a next-generation experimental program to observe cosmic microwave background radiation, the “fossil light” from the early universe.  This would include an installation of a new set of telescopes at the South Pole, as part of a larger global array, which will allow highly sensitive measurements that could detect signatures of gravitational waves.  Such observations might provide evidence that could confirm the theory of cosmic inflation and the quantum nature of gravity, as well as address other enduring questions about the nature of the universe.
 
“Although remote, the changes occurring in the Southern Ocean and Antarctica can directly influence the United States,” said committee co-chair Robert Weller, senior scientist at Woods Hole Oceanographic Institution in Massachusetts.  “But these are challenging areas to do research, so there is a pressing need to prioritize the allocation of resources in order to assure reliable, safe support for critical observations and research campaigns.”
 
The report recommends the following as key needs for supporting and implementing the priority research goals and other areas of Antarctic and Southern Ocean science:   
•         Expanded access to remote field sites, including a deep field camp and logistics hub, over-snow traverse capabilities, and improved all-weather access to research stations and field locations by air;
•         Design and acquisition of a new heavy icebreaker ship and an ice-capable polar research vessel;
•         Support for sustained observations through strategic augmentation and coordination of existing observational networks;
•         Improved communications and information technology for data transmission; and
•         Efforts to facilitate more open and coordinated data collection, sharing, and integration.
 
The report notes that the priority research initiatives all require some degree of collaboration among NSF divisions, with other U.S. agencies, and with other nations.  In addition, NSF can play an important role in developing Antarctic-themed educational resources for K-12, undergraduate and graduate programs, and informal education institutions."


http://www.nap.edu/catalog/21741/a-strategic-vision-for-nsf-investments-in-antarctic-and-southern-ocean-research

Committee on the Development of a Strategic Vision for the U.S. Antarctic Program; Polar Research Board; Division on Earth and Life Studies; National Academies of Sciences, Engineering, and Medicine

A Strategic Vision for NSF Investments in Antarctic and Southern Ocean Research (2015)
Description
Antarctic and Southern Ocean scientific research has produced a wide array of important and exciting scientific advances. Spanning oceanography to tectonics, microbiology to astrophysics, the extreme Antarctic environment provides unique opportunities to expand our knowledge about how our planet works and even the very origins of the universe. Research on the Southern Ocean and the Antarctic ice sheets is becoming increasingly urgent not only for understanding the future of the region but also its interconnections with and impacts on many other parts of the globe.
Prepublication: 978-0-309-37784-3
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

solartim27

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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #151 on: October 02, 2015, 10:07:55 PM »
I was having trouble getting a Sentinel shot to line up, so chose to take a look at Worldview.  It looks to me like the whole of Thwaits moved recently.  I looked at some nearby areas, and saw no similar shift, so I don't think it's some sort of data error.

Here is a Gif looking at 2013, 2014 and then 2 recent shots.  Don't pay as much attention to the calving front as to the surface elements on the right side.  I'd be happy to be shown that I am but a crude ignoramus in this case.  Click is required.

Edit:  I tried looking between Sep 22 and Oct 1 versus Sep 24 and Oct 1, and saw little if any motion, which leads me to believe there is some sort of matching error.  Or could it be a tidal influence?
« Last Edit: October 02, 2015, 10:36:15 PM by solartim27 »
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #152 on: October 02, 2015, 11:40:46 PM »
solartim27,

I provide that attached first image of Thwaites Terra Oct 2 2014 and the second image of a blue filter Thwaites Aqua Oct 3, 2015.

These images indicate to me that the grounded iceberg at the outboard end of the residual Thwaites Ice Tongue has likely fractured and moved outward.  If so this is a bad sign for the stability of the residual Thwaites Ice Tongue, the nearby iceberg mélange and for Thwaites itself, this coming austral summer.

Best,
ALSR

Edit: The third image of Thwaites Eastern Ice Shelf & Ice Residual Tongue is from Sentinel 1a on Sept 26 2015, showing that the grounded iceberg is starting to move outward by that date.
« Last Edit: October 02, 2015, 11:46:39 PM by AbruptSLR »
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solartim27

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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #153 on: October 03, 2015, 10:37:55 PM »
Here is a Sentinel gif from Aug 24 to Oct 3.  Time to invest in companies that make water wings?  I estimate the verticle edge to cover about 80 miles.

I left it as a large size, so click to animate.

Correction, should be Aug 28
« Last Edit: October 03, 2015, 10:45:43 PM by solartim27 »
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #154 on: October 04, 2015, 12:58:40 AM »
Here is another gif, zoomed in a bit, and shifted to include the large ice island.  Has anyone researched developing gills like in the movie waterworld yet?

Click to animate.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #155 on: October 04, 2015, 05:35:51 PM »
Here is a Sentinel gif from Aug 24 to Oct 3.  Time to invest in companies that make water wings?  I estimate the verticle edge to cover about 80 miles.

I left it as a large size, so click to animate.

Correction, should be Aug 28

solartim27,

Thanks for the great animation, which to my eyes indicates not only that the grounded iceberg at the outer end of the residual Thwaites Ice Tongue has slide seaward & may have become ungrounded, but also that:
1. The ice stream feeding the Thwaites Ice Tongue has surged downstream.
2. The advection of warm CDW (possibly associated with our strong El Nino event) as created a polynyas at the seaward end of the Thwaites Ice Tongue, which is most likely contributing to high rates of basal ice melting for the glacial ice in this area.
3. The surge of the residual Thwaites Ice Tongue debris field is prying a large iceberg at the Southwest corner of the base of the Eastern Thwaites Ice Shelf, ETIS; which could accelerate a major calving event for the ETIS possibly as early as this coming austral summer.
4. During the August 28 to Oct 3 timeframe (which the illustrated surge apparently occurred) the local winds were directed offshore, which probably accounts for the widespread movement of the icebergs in the mélange to west of the residual Thwaites Ice Tongue (& also indicating how weak the sea ice is in this area, possibly due to basal melting).

Best,
ASLR
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #156 on: October 14, 2015, 06:19:26 PM »
The attached Aqua image of Thwaites taken Oct 14 2015, indicates to me that the mélange of icebergs forming the residual Thwaites Ice Tongue, continues to move seaward, and that the polynyas at the seaward end of the Ice Shelf/residual Ice Tongue indicate to me that there is substantial advected warm CDW in this area (melting the local sea ice)
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #157 on: October 17, 2015, 09:17:52 PM »
I provide the attached Aqua image of Thwaites for Oct 16 2015, because it is clearer than the images on Oct 15 or 17, and as it indicates that the previously grounded iceberg at the seaward end of the residual Thwaites Ice Tongue is not only slowly moving seaward but also westward.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #158 on: October 18, 2015, 09:19:18 PM »
No big change, still lots of motion.  Had a nice match between Oct 6 and 18 Sentinel shots.  I estimate the calving is 1km by 2 km.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #159 on: October 18, 2015, 11:49:49 PM »
Here's the area zoomed in a bit, again Oct 6 to 18.  I believe the  top of this image would be around the lower right corner of the Aqua images above posted by ASLR.  Left it as a larger size, so will need a click to animate.
« Last Edit: October 18, 2015, 11:56:58 PM by solartim27 »
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #160 on: October 22, 2015, 11:10:35 PM »
There is too much cloud cover today for any clear satellite images of the ASE; so instead I provide the attached Earth Surface Wind & MSLP Map (from nullschool) for Oct 22 2015; showing how the ABSL is perfectly positioned so that surface winds are driving warm CDW directly into the ASE, thus promoting basal Ice Shelf melting and grounding line retreat for associated marine glaciers.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #161 on: October 27, 2015, 07:49:03 PM »
Here is an overview of the Thwaites area from Oct 3 to 27.  Click to animate.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #162 on: October 30, 2015, 09:26:23 PM »
Nice cloud free day at PIG.  here is a gif from Sep 22 to Oct 30. 

Doesn't animate for me, it should though, weird. ( Clicking doesn't work either ) It's still a nice clear shot though.
« Last Edit: October 30, 2015, 09:35:37 PM by solartim27 »
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #163 on: November 01, 2015, 07:23:08 PM »
If you compare the attached Terra image of Thwaites for Nov 1 2015 with the comparable Oct 16 2015 image shown in Reply #157, it is clear that the iceberg that was previously pinned at the seaward end of the residual Thwaites Ice Tongue in now moving westward, indicating that it is no longer pinned and may likely float away when the surrounding sea ice melts this coming austral summer.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #164 on: November 02, 2015, 04:39:15 PM »
The attached nullschool image issued today shows the Earth Surface Wind & Temperature Map forecast for Nov 4 2015; illustrating how our current Super El Nino event can both telecommunicate tropic atmospheric energy, and the surface winds can direct warm CDW, directly into the ASE where it will accelerate ice mass loss from key marine glaciers there, including PIG & Thwaites
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #165 on: November 02, 2015, 05:34:35 PM »
Today's Terra image of the Thwaites Ice Shelf and Residual Ice Tongue, show that the local sea ice is beginning to fracture:
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #166 on: November 04, 2015, 07:55:11 PM »
What is the background on the big berg, and am I right thinking that it is about 20 miles by 60 miles?  I assume it is an older part of Thwaites.  The southern part moved alot, possibly still pinned on the bottom offscreen.

Toggling worldview between the 3rd and 4th makes it look like it's blowing back towards land, but there seems to be an alignment error zooming out to a larger area.  The current wind certainly makes that possible.

Gif dates are Oct 27 to Nov 3
« Last Edit: November 04, 2015, 08:23:23 PM by solartim27 »
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #167 on: November 04, 2015, 10:52:37 PM »
What is the background on the big berg, and am I right thinking that it is about 20 miles by 60 miles?  I assume it is an older part of Thwaites.  The southern part moved alot, possibly still pinned on the bottom offscreen.

Toggling worldview between the 3rd and 4th makes it look like it's blowing back towards land, but there seems to be an alignment error zooming out to a larger area.  The current wind certainly makes that possible.

Gif dates are Oct 27 to Nov 3

I think that what you are showing broke-off from the Thwaites Ice Tongue in 2002, and think that it is about 30 miles by about 17 miles in plan dimensions.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #168 on: November 13, 2015, 08:36:12 AM »
Thwaites has a new calving, and a big crack advance.  Dates are 11/11 and 10/30.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #169 on: November 14, 2015, 10:19:58 PM »
Had a nice clear day for world view.  Here is a gif from 11/3 to 11/14.  I left it large so that you could see the changes, so click to animate
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #170 on: November 24, 2015, 09:51:56 PM »
Cross posted from the PIG thread, because I noticed the tabular bergs to the northwest(?) (or on the right about 1/2 way down) breaking up like the recent Zachariae Isstrom thread.  Here is the small gif, for the full size one go to the PIG post.
The pinned berg is showing a good bit of rotation on todays world view.

Meanwhile, in case you've missed the Thwaites thread, there's going to be some more calving there soon, and the big berg off of there is moving out.  Here are two of the same gifs from Oct 24 to Nov 11, one should animate, and one is saved full size (2.7 Mb) if you want to zoom in closer.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #171 on: November 25, 2015, 11:28:10 PM »
Pollard et al. (2015) looked to the Pliocene for an example of abrupt SLR associated with Marine Ice Sheet Instability, MISI; while Hansen et al. (2015) turned to the Eemian for another example abrupt SLR due to MISI.  Unfortunately, the further back in time that modelers look to calibrate their projections the more uncertainties creep into the MISI response issue (giving denialist wiggle room for doubt).  However, one underutilized opportunity to calibrate ice sheet models with cliff failure mechanisms is the Holocene Optimum when the Jakobshavn Glacier abruptly retreated down the sill of its fjord shown in the first attached image.  Ice sheet models (with cliff failure mechanisms) calibrated to match this relatively recent event could then be applied to both the PIG and the Thwaites Glacier cases beginning around 2040 (see Replies #406, 408, 418 and 449-453 in the "PIG has Calved" thread for recent discussions of the timing of cliff failure for the PIG and Replies #5 and 13 in this thread for discussion of the timing of cliff failures for the Thwaites Glacier).

With a hat-tip to Sleepy's Reply #115 in the "what's new in Greenland?" thread:
(1) The first linked reference [Ouellet-Bemier et al. (2014), see the second image for the study area], points out that following a few thousand year long period while Disko Bugt was cleared of ice from about 10,000 years ago to about 7,300 year ago, there came an abrupt ice mass loss event from as the Jakobshavn Glacier retreated down the sill shown in the first image circa 7,300 years ago (near the Holocene Optimum). 
(2) The second linked reference [Kelley et al. (2013), see the third image for the study area] provides more details of the moderately dynamic ice mass loss from Disko Bugt from 10,800 to about 9,200 years ago.
Again, modelers such as Gomez, DeConto, Pollard and Alley should take advantage of this relatively recent example of a cliff failure driven abrupt ice mass loss event down a sustained negative slope:

Marie-Michèle Ouellet-Bemier, Anne de Vernal, Claude Hillaire-Marcel and Matthias Moros (September 2014), "PALEOCEANOGRAPHIC CHANGES IN THE DISKO BUGT AREA, WEST GREENLAND, DURING THE HOLOCENE", University of Quebec at Montreal, Canada.

http://www.archipel.uqam.ca/6996/1/M13491.pdf

Extract: "In surface waters of the Disko Bugt, the northward penetration of the WGC likely occurred at about 7300 cal. yr BP as shown by the dinocyst-based reconstruction of SSTs and sea ice cover.



Data indicate glaciomarine conditions until -10 000 cal. yr BP while the earliest evidence of some Atlantic influence through the WGC appeared in deep water, when the benthic foraminifer Islandiella norcrossi was first recorded in the core. The WGC influence was recorded much later in surface waters, which were characterized locally by cold conditions with a dense ice cover until -7300 cal. yr BP, likely because of important discharge of ice and meltwater from the GIS."


Also see:

Samuel E. Kelley, Jason P. Briner and Nicolás E. Young (2013), "Rapid ice retreat in Disko Bugt supported by 10Be dating of the last recession of the western Greenland Ice Sheet", Quaternary Science Reviews, 82, pp. 13 to 22

http://www.uib.no/sites/w3.uib.no/files/attachments/kelley_13.pdf

Abstract: "Due to rising sea levels and warming ocean currents, marine-based sectors of the Greenland and Antarctic ice sheets are particularly vulnerable to warming climate. Reconstructions of the timing of marine based ice margin fluctuations in Greenland during the early Holocene can provide context for historical and modern observations of ice-sheet change. Here, we generate a 10Be chronology of ice-sheet retreat through Disko Bugt, western Greenland. Our new chronology, consisting of twelve 10Be ages from sites surrounding and within Disko Bugt, fills a gap in the history of the western margin of the Greenland Ice
Sheet and allows for a continuous composite record of ice-margin recession between the continental shelf break and the current margin. We constrain the onset of ice-margin retreat from outer Disko Bugt to 10.8 _ 0.5 ka. When combined with previous chronologies, these results place the final Greenland Ice
Sheet retreat out of Disko Bugt onto land at Jakobshavn Isfjord and Qasigiaanguit at 10.1 _ 0.3 ka, and later at 9.2 _ 0.1 ka in southeastern Disko Bugt. The rate of retreat during this time period is between ~ 50 to 450 m a_1 for central Disko Bugt and ~50 to 70 m a_1 along the southern coast of Disko Bugt.
Deglaciation of Disko Bugt occurred ~1000 years later than in neighboring Uummannaq Fjord to the north. This asynchrony in the timing of deglaciation suggests that local ice dynamics played an important role in the retreat of the Greenland Ice Sheet from large marine embayments in western Greenland."

Conclusions: "New 10Be ages from around Disko Bugt, western Greenland, place the deglaciation of western Disko Bugt at 10.8 _ 0.5 ka, with the ice margin reaching the eastern coast of Disko Bugt near Ilulissat at 10.1 _0.3 ka and in southeastern Disko Bugt at 9.2 _ 0.1 ka.
This chronology yields a retreat rate between ~50 and 450 m a_1 across central Disko Bugt. This rate indicates that ~ 25% of the overall retreat between the shelf edge and the current position occurred in as little as 700 years. We suggest this retreat was the result of internal ice dynamics acting upon an ice sheet driven out of equilibrium by climatic factors. These findings further emphasize the ability of marine sectors of ice sheets to change rapidly due to ice dynamics in warming climates (e.g. Kjær et al., 2012). Our chronology fills a gap in the current understanding of the early Holocene behavior of the GrIS in Disko Bugt, and provides a dataset that completes a history of a western GrIS margin spanning from the continental shelf to the present ice position, and from the latest Pleistocene through the Holocene."
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #172 on: December 09, 2015, 07:36:28 PM »
The cracks at Thwaites have calved off, and the large berg continues to float away.
Gif from Dec 2 to Dec 9.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #173 on: December 09, 2015, 09:34:27 PM »
Here's a zoomed in gif from the previous post.  Looking at Worldview, I estimate the vertical scale to be around 10 miles.  Anyone have a better measurement?
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #174 on: December 22, 2015, 11:18:49 PM »
The two attached Sentinel images of Thwaites from Nov 19 and Dec 20 2015, respectively, indicate that the pinned iceberg at the outer end of the residual Thwaites Ice Tongue is moving westward and slightly northward, thus relieving compressive stresses from the smaller icebergs within the body of the residual Thwaites Ice Tongue.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #175 on: December 28, 2015, 05:54:03 PM »
The attached mosaic shows that the ASE (Pine Island Bay) sea ice is starting to break-up; which might eventually allow some of the icebergs trapped in the fast sea ice to float away.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #176 on: January 05, 2016, 12:52:33 AM »
As the Landsat8 image of the Thwaites Ice Shelf/Tongue for Jan 4, 2016 is now available, I provide the attached extract to show that the adjoining sea ice is rapidly melting and will likely start to release entrapped icebergs before too long.  For those who are interested a comparable image for the PIIS on Jan 4 2016 is also available for download (but I am not posting it as it indicates to me that another major calving event for the PIIS will not result in a major iceberg that can float away before the austral Spring of 2016)
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #177 on: January 19, 2016, 05:07:11 PM »
The first attached images shows a Sentinel image showing that the sea ice in the Thwaites/Haynes/Pope area is now breaking up sufficient to release many previously trapped icebergs.  With continued melting of more fast sea ice, I expect more and more currently trapped icebergs to float away, which will reduce the associated buttressing action from this ice mélange in front of these key marine glaciers.  The second attached image is from Google Earth showing a rotated view of this area from several years ago (provided for comparison):
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #178 on: January 20, 2016, 11:52:22 PM »
The first attached Terra image for Jan 20 2016 has a lot of clouds, but I think that it clearly shows a major loss of sea ice to the west of Thwaites (since the 18th).

The second image shows the Earth 1000-hPa Wind & Temperature Map for Jan 20 2016, showing anomalously high temperatures along the coastline in the ASE.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #179 on: February 15, 2016, 09:14:30 PM »
Another 'small' calving at Thwaites.  I was surprised it took this long to develop.  It looks to me like it might just be the start of a larger event?  Dates are Feb 8 to Feb 15.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #180 on: February 17, 2016, 07:39:36 PM »
Worldview had a nice clear view of the last calving today, so I went back to Jan 29 for a comparision shot.  Added a frame of Jacobshavn Isbrae for comparision purposes.
« Last Edit: February 17, 2016, 07:52:28 PM by solartim27 »
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #181 on: February 22, 2016, 07:59:20 PM »
I am posting the attached Aqua image of the Thwaites area from Feb 22 2016, mainly because it has been cloudy there and this shows the current status of the adjoining sea ice.  We will see whether any of it floats away before the austral winter refreeze begins:
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #182 on: March 02, 2016, 08:41:56 PM »
Here is a small calving from an area that had no visible cracks.  There also seems to be a some advance over the whole area, but part of that may be an imprecise overlay on my part.  Calved bit about 1 mile long?
Dates are Feb 24 and Mar 2.
« Last Edit: March 02, 2016, 08:48:47 PM by solartim27 »
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #183 on: March 16, 2016, 04:03:46 PM »
While sidd has previously discussed the linked reference in the "What's new in Antarctica?" thread, I repost it here due its particular importance to both the Pine Island and Thwaites ice shelves:

Karen E. Alley, Ted A. Scambos, Matthew R. Siegfried & Helen Amanda Fricker (2016), "Impacts of warm water on Antarctic ice shelf stability through basal channel formation", Nature Geoscience, doi:10.1038/ngeo2675

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2675.html

Abstract: "Antarctica’s ice shelves provide resistance to the flow of grounded ice towards the ocean. If this resistance is decreased as a result of ice shelf thinning or disintegration, acceleration of grounded ice can occur, increasing rates of sea-level rise. Loss of ice shelf mass is accelerating, especially in West Antarctica, where warm seawater is reaching ocean cavities beneath ice shelves. Here we use satellite imagery, airborne ice-penetrating radar and satellite laser altimetry spanning the period from 2002 to 2014 to map extensive basal channels in the ice shelves surrounding Antarctica. The highest density of basal channels is found in West Antarctic ice shelves. Within the channels, warm water flows northwards, eroding the ice shelf base and driving channel evolution on annual to decadal timescales. Our observations show that basal channels are associated with the development of new zones of crevassing, suggesting that these channels may cause ice fracture. We conclude that basal channels can form and grow quickly as a result of warm ocean water intrusion, and that they can structurally weaken ice shelves, potentially leading to rapid ice shelf loss in some areas."

See also:
https://www.washingtonpost.com/news/energy-environment/wp/2016/03/14/antarcticas-ice-is-being-carved-up-from-below/
Extract: "In the new study, led by Karen Alley of the National Snow and Ice Data Center at the University of Colorado in Boulder, the researchers document that the warm ocean water that’s undermining West Antarctica from below may also be weakening its ice shelves. It appears to be slowly carving deep channels into their bases, cavities ranging from 50 to 250 meters in vertical extent.
These channels appear to be formed as the warm water that hits the grounding line then bursts upward in a plume, combined with meltwater, and cuts into the ice shelf from below, Alley said. “They’re kind of like upside down rivers, or streams. Instead of the water flowing downhill, it’s flowing uphill, because it’s buoyant,” she says."
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #184 on: March 17, 2016, 11:45:27 PM »
(Sorry if this has already been posted)

Quote
When I asked Richard Alley, almost certainly the most respected glaciologist in the United States, whether he would be surprised to see Thwaites collapse in his lifetime, he drew a breath. Alley is 58.

‘‘Up until very recently, I would have said, ‘Yes, I’d be surprised,’ ’’ he told me. ‘‘Right now, I’m not sure. I’m still cautiously optimistic that in my life, Thwaites has got enough stability on the ridge where it now sits that I will die before it does. But I’m not confident about that for my kids. And if someday I have grandkids, I’m not at all confident for them.’’

http://mobile.nytimes.com/2015/11/15/magazine/the-secrets-in-greenlands-ice-sheets.html?referer=&_r=1

So he's not sure that he would be surprised if Thwaites collapsed within the next 20-30 years!

I find that rather...surprising!
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #185 on: March 24, 2016, 05:20:40 PM »
The accompanying images come from the linked World Meteorological Organization's Polar Space Task Group (PSTG) reports.  The second link provides the first two images.  The first image indicates that thru 2012 most of the ice mass loss in Antarctic Ice Shelves has been concentrated in West Antarctica; which means that the associated marine glaciers are losing buttressing faster than other Antarctic marine glaciers.  The second image indicates that from 2010 to 2013 the WAIS contributed 0.45mm/yr to SLR.  The last two images come from the third link.  The third image indicates that the ice velocities for the PIG accelerated during the period when the groundling was retreating down the negative slope of the seafloor and then stabilized thru August 2015.  The fourth image shows that while the grounding line for the Thwaites Glacier has not yet reached the negative slope of the seafloor; nevertheless, its ice velocities have accelerated since 2006 as it has progressively lost buttressing from the Thwaites Ice Tongue:

http://www.wmo.int/pages/prog/sat/pstg_en.php


http://www.wmo.int/pages/prog/sat/meetings/documents/PSTG-5_Doc_06_EC-PHORS-ppt.pdf


http://www.wmo.int/pages/prog/sat/meetings/documents/PSTG-5_Doc_13-01_BScheuchl-Ice-Sheets-Final.pdf

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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #186 on: March 28, 2016, 06:05:30 PM »
The attached Sentinel 1a image of Thwaites for March 25 2016, shows that the grounded iceberg at the seaward end of the residual Thwaites Ice Tongue has recently sustained a major calving event.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #187 on: March 29, 2016, 02:20:12 AM »
The attached Sentinel 1a image of Thwaites for March 25 2016, shows that the grounded iceberg at the seaward end of the residual Thwaites Ice Tongue has recently sustained a major calving event.

The calving event actually took place already in January as shown in this animation of MODIS Terra images from January 9-12. For some reason the big piece never completely separated until now.

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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #188 on: April 04, 2016, 05:45:39 AM »
To me the most significant hazard is Thwaites. Any teams trying to send submersibles under there in the next couple years ? A thermal profile a la Dutreux for PIG would be very nice.

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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #189 on: April 04, 2016, 09:56:47 AM »
To me the most significant hazard is Thwaites. Any teams trying to send submersibles under there in the next couple years ? A thermal profile a la Dutreux for PIG would be very nice.

Per the two attached images (that you are familiar with) DeConto & Pollard (2016) seem to believe that the Antarctic Peninsula (AP), the Amundsen Sea Embayment (ASE) outlet glaciers (including the PIG), the Totten (T), and the Siple Coast (SC) and Weddell Sea (WS) grounding zones, will reach peak discharge before peak discharge occurs for the deep Thwaites Glacier basin (TG).  But of course they could be mixed-up in their order, and/or discharge magnitudes (or maybe TG just discharges for a very long time, or not).
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #190 on: April 20, 2016, 08:27:19 PM »
I think it would be safe to adjust the dates on this thread earlier by a decade or two.

Here is a nice lineup from Apr 7 to 19 showing lots of motion across most of the glacier, one file reduced in size, one original size (2.4 Mb).

Source:  http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20160419T044345_3B62_S_1.final.jpg

and S1A_EW_GRDM_1SSH_20160407T044345_1C67_S_1.final.jpg
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #191 on: April 22, 2016, 05:06:15 PM »
I think it would be safe to adjust the dates on this thread earlier by a decade or two.

solartim27,

Thanks for the animation showing that the pinned iceberg is beginning to move; however, while you might be right that cliff faces may occur at the base of the residual Thwaites Ice Tongue by 2020, that is a far different matter than: (a) having cliff faces across the entire 50km Thwaites Gateway and (b) having hydrofracturing occurring which requires GMST being 2 to 3C above pre-industrial.  As previously noted, the linked article discusses how NOAA notified the insurance industry  that sea level might possibly rise by 3m in the 2050-2060 timeframe due to instabilities in the WAIS; which reasonably matches my 2040-2060 timeframe for the end of the initial stage of PIG/Thwaites collapse.

http://www.insurancejournal.com/news/national/2016/04/12/405089.htm

Extract: "Think sea level rise will be moderate and something we can all plan for? Think again.
Sea levels could rise by much more than originally anticipated, and much faster, according to new data being collected by scientists studying the melting West Antarctic ice sheet – a massive sheet the size of Mexico.
That revelation was made by an official with the National Oceanic and Atmospheric Administration on Tuesday at the annual RIMS conference for risk management and insurance professionals in San Diego, Calif.
The conference is being attended by more than 10,000 people, according to organizers. It was day No. 3 of the conference, which ends Wednesday.
Margaret Davidson, NOAA’s senior advisor for coastal inundation and resilience science and services, and Michael Angelina, executive director of the Academy of Risk Management and Insurance, offered their take on climate change data in a conference session titled “Environmental Intelligence: Quantifying the Risks of Climate Change.”
Davidson said recent data that has been collected but has yet to be made official indicates sea levels could rise by roughly 3 meters or 9 feet by 2050-2060, far higher and quicker than current projections. Until now most projections have warned of sea level rise of up to 4 feet by 2100.
These new findings will likely be released in the latest sets of reports on climate change due out in the next few years.
“The latest field data out of West Antarctic is kind of an OMG thing,” she said.
Davidson’s purpose was to talk about how NOAA is sharing information with the insurance community and the public, and to explain how data on climate change is being collected.
She explained that reports like those from the Intergovernmental Panel on Climate Change and the National Climate Assessment, which come out roughly every five years, are going on old data.
By the time the scientists compiling those reports get the data it’s roughly two years old, because it took those gathering the data that long to collect it. It takes authors of the reports a few years to compile them.
“By the time we get out the report, it’s actually synthesizing data from about a decade ago,” she said.
Angelina’s focus was also on the data. He spoke about the ongoing development of the Actuaries Climate Index and the Actuaries Climate Risk Index.
The goals of the projects are to create climate change indices that reflect an actuarial perspective, to create an index that measures changes in climate extremes, use indices to inform the insurance industry and the public, and promote the actuarial profession by contributing statistically to the climate change debate.
So far their findings show the climate is definitely changing – though neither Davidson nor Angelina addressed the cause of this change, which they said was not the purpose of their talk.
Angelina said a new way of looking at weather is required when dealing with climate change, and that just looking at averages isn’t enough to give an accurate picture of climate change and the risk it presents.
The projects he’s involved with have instead looked at weather extremes.
“By looking at extremes I can actually acknowledge that I have a problem,” he said.
He used the notorious Bell Curve grading system to illustrate his point.
The goal of the curve is to achieve a 70 percent average among students. But if a teacher got to that 70 percent figure by having half the students failing poorly and half doing excellently, there’s a problem: half of the students aren’t getting it.
Looking at extreme temperature indices from more than 40 years ago and now, “things are different,” he said.
So too are days of excessive rain, and excessive dry days, wind power and the sea level index.
“They’re all up,” he said.
He added: “We’re in a different climate. The climate has changed.”

The main phase of PIG/Thwaites collapse is discussed here (which includes cliff failures & hydrofractuing; which I called the Thwaites Effect & melt ponds):

http://forum.arctic-sea-ice.net/index.php/topic,85.0.html

Edit: For what it is worth I re-attach my expectation from three years ago of what the grounding lines this area might look like by 2040.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #192 on: June 02, 2016, 07:14:46 AM »
For years now I have been whining about the lack of full stokes analyses for ice flow (mostly because i am too lazy to attempt the effort.) Lo, and behold

http://www.the-cryosphere-discuss.net/tc-2016-101/

Usual suspects. Open access. Full Stokes(2D flowband, but perhaps they will do 3D). Top and bottom crevasses (but no surface melt or hydrofrac yet). Experiments with basal melt changes. Disparaging remarks about comparison models. Read all about it.

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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #193 on: June 02, 2016, 05:11:15 PM »
For years now I have been whining about the lack of full stokes analyses for ice flow (mostly because i am too lazy to attempt the effort.) Lo, and behold

sidd,
Thanks for the great catch.  I seems like every time that we improve our models the Thwaites looks less and less stable.  For those who do not like to click, I provide the following abstract:
Best,
ASLR

Yu, H., Rignot, E., Morlighem, M., and Seroussi, H.: Full-Stokes modeling of grounding line dynamics, ice melt and iceberg calving for Thwaites Glacier, West Antarctica, The Cryosphere Discuss., doi:10.5194/tc-2016-101, in review, 2016.

http://www.the-cryosphere-discuss.net/tc-2016-101/

Abstract. Thwaites Glacier (TG), West Antarctica, has been losing mass and retreating rapidly in the past three decades. Here we present a two-dimensional, Full-Stokes (FS) modeling study of the grounding line dynamics and iceberg calving of TG. First, we compare FS with two simplified models, the higher-order (HO) model and the shallow-shelf approximation (SSA) model, to determine the impact of changes in ice shelf basal melt rate on grounding line dynamics. Second, we combine FS with the Linear Elastic Fracture Mechanics (LEFM) theory to simulate crevasse propagation and iceberg calving. In the first experiment, we find that FS requires basal melt rate consistent with remote sensing observations to reach steady state at TG’s current geometry while HO and SSA require unrealistically high basal melt rate. The grounding line of FS is also more sensitive to changes in basal melt rate than HO and SSA. In the second experiment, we find that only FS can produce surface and bottom crevasses that match radar sounding observations of crevasse width and height. We attribute the difference to the non- hydrostatic conditions of ice near the grounding line, which facilitate crevasse formation and are not accounted for in HO and SSA. Additional experiments using FS indicate that iceberg calving is significantly enhanced when surface crevasses exist near the grounding line, when ice shelf is shortened, or when the ice shelf front is undercut. We conclude that FS yields substantial improvements in the description of ice flow dynamics at the grounding line under high basal melt rate and in constraining crevasse formation and iceberg calving.
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #194 on: June 02, 2016, 06:13:46 PM »
If posted elsewhere sorry. Abrupt Sea Level Rise Looms
As Increasingly Realistic Threat

Quote
For the Pliocene era 3 million years ago, for example — when seas were dozens of feet higher than today — older models estimated that a partially melting Antarctic added about 23 feet to global sea level rise. The new model increased Antarctica’s contribution to sea level rise during the Pliocene to 56 feet.
Quote
Even DeConto admits that, under the model used in his paper, the timing and pace of Antarctica’s ice loss is “really uncertain” — it could be a decade or two, or three or four, before these dramatic processes start to kick in, he says. “The paper just shows the potentials, which are really big and really scary,” says DeConto. But Scambos and other observers call DeConto’s numbers “perfectly plausible.”
Two articles referred to:
Contribution of Antarctica to past and future sea-level rise
Quote
Abstract
Abstract• Change history• References• Author information• Extended data figures and tables• Supplementary information
Polar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sea level has been 6–9 metres higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago). In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability. Here we use a model coupling ice sheet and climate dynamics—including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs—that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.
Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 ◦C global warming could be dangerous
Quote
Abstract. We use numerical climate simulations, paleoclimate data, and modern observations to study the effect of growing ice melt from Antarctica and Greenland. Meltwater tends to stabilize the ocean column, inducing amplifying feedbacks that increase subsurface ocean warming and ice shelf melting. Cold meltwater and induced dynamical effects cause ocean surface cooling in the Southern Ocean and North Atlantic, thus increasing Earth's energy imbalance and heat flux into most of the global ocean's surface. Southern Ocean surface cooling, while lower latitudes are warming, increases precipitation on the Southern Ocean, increasing ocean stratification, slowing deepwater formation, and increasing ice sheet mass loss. These feedbacks make ice sheets in contact with the ocean vulnerable to accelerating disintegration. We hypothesize that ice mass loss from the most vulnerable ice, sufficient to raise sea level several meters, is better approximated as exponential than by a more linear response. Doubling times of 10, 20 or 40 years yield multi-meter sea level rise in about 50, 100 or 200 years. Recent ice melt doubling times are near the lower end of the 10–40-year range, but the record is too short to confirm the nature of the response. The feedbacks, including subsurface ocean warming, help explain paleoclimate data and point to a dominant Southern Ocean role in controlling atmospheric CO2, which in turn exercised tight control on global temperature and sea level. The millennial (500–2000-year) timescale of deep-ocean ventilation affects the timescale for natural CO2 change and thus the timescale for paleo-global climate, ice sheet, and sea level changes, but this paleo-millennial timescale should not be misinterpreted as the timescale for ice sheet response to a rapid, large, human-made climate forcing. These climate feedbacks aid interpretation of events late in the prior interglacial, when sea level rose to +6–9 m with evidence of extreme storms while Earth was less than 1 °C warmer than today. Ice melt cooling of the North Atlantic and Southern oceans increases atmospheric temperature gradients, eddy kinetic energy and baroclinicity, thus driving more powerful storms. The modeling, paleoclimate evidence, and ongoing observations together imply that 2 °C global warming above the preindustrial level could be dangerous. Continued high fossil fuel emissions this century are predicted to yield (1) cooling of the Southern Ocean, especially in the Western Hemisphere; (2) slowing of the Southern Ocean overturning circulation, warming of the ice shelves, and growing ice sheet mass loss; (3) slowdown and eventual shutdown of the Atlantic overturning circulation with cooling of the North Atlantic region; (4) increasingly powerful storms; and (5) nonlinearly growing sea level rise, reaching several meters over a timescale of 50–150 years. These predictions, especially the cooling in the Southern Ocean and North Atlantic with markedly reduced warming or even cooling in Europe, differ fundamentally from existing climate change assessments. We discuss observations and modeling studies needed to refute or clarify these assertions.
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solartim27

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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #195 on: June 12, 2016, 09:18:19 PM »
General advance, with one 'small' calving towards the center of the image.
Dates are May 30 and Jun 11
S1A_EW_GRDM_1SSH_20160611T045153_EC09_S_1.final
S1A_EW_GRDM_1SSH_20160530T045153_044B_S_1.final
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #196 on: June 30, 2016, 11:37:58 PM »
More ice movement, more calving.  Jun 30 vs Jun 11
S1A_EW_GRDM_1SSH_20160630T044349_949F_S_1.final.jpg
S1A_EW_GRDM_1SSH_20160611T045153_EC09_S_1.final.jpg
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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #197 on: July 10, 2016, 11:50:45 PM »
The linked ESA website provides both Sentinel 1a photos and ice velocity data for Thwaites Glacier (see first two attached images from March 29 2016, of along flow and across flow ice speeds) and for PIG (see last two attached images from April 26 2016).  While all images show that these two marine glacier are fluctuating about average conditions, the across flow velocities for Thwaites appear to indicate some local acceleration near the base of the residual ice tongue.  The data is regularly updated and may soon including information from Sentinel 1b:

http://www.cpom.ucl.ac.uk/csopr/iv/index.html

For Thwaites
http://www.cpom.ucl.ac.uk/csopr/iv/index.html?glacier_number=4

For PIG
http://www.cpom.ucl.ac.uk/csopr/iv/index.html?glacier_number=3


See also:
http://www.bbc.com/news/science-environment-36051112

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Re: Hazard Analysis for PIG/Thwaites from 2012 to 2040-2060 Timeframe
« Reply #198 on: July 17, 2016, 09:26:36 PM »
Another big calving with general advance.  One wide area gif, and one zoomed in.
6/30 to 7/17.
http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20160717T045158_6AF6_S_1.final.jpg

S1A_EW_GRDM_1SSH_20160630T044349_949F_S_1.final.jpg
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