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Author Topic: Epiq Sermia / West Greenland  (Read 6862 times)

nukefix

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Epiq Sermia / West Greenland
« on: May 04, 2016, 10:36:55 AM »
Interesting, this S-1a image shows concentric waves close to the calving front that must have been generated by a small calving event at the time of the imaging.
« Last Edit: May 04, 2016, 11:08:24 AM by nukefix »

A-Team

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Re: Epiq Sermia / West Greenland
« Reply #1 on: May 04, 2016, 04:06:41 PM »
Quote
concentric waves close to the calving front that must have been generated by a small calving event at the time of the imaging

That has to be the correct interpretation ... but the timing seems miraculous, to catch these waves which could not have persisted very long yet before they reflected off the shore or diffracted around. Maybe there were steady calving events  for hours so orbital timing wasn't so critical.

I believe they have a web cam there at the lodge. Was this night ... seems like the UTC time was cut off of the S1A file name above. We should also check S2A and Landsat in and around this 27 Apr 16 date. They pass overhead with about a  ten minute lag (both near local noon).
« Last Edit: May 04, 2016, 04:13:52 PM by A-Team »

nukefix

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Re: Epiq Sermia / West Greenland
« Reply #2 on: May 05, 2016, 12:06:12 PM »
Imaging of one S-1 burst takes less than 3 seconds so it is indeed fortuitous ...I think this is an example of "the law of large number of calving fronts" in action.

Incidentally the same S-1 scene has further examples of this, the attached image is a couple of calving fronts towards the north and the lower arrow indicates another set of concentric waves, and the top arrow points to a semi-circular feature in the sea ice that looks like  concentric waves from a recent calving have broken/disturbed the sea-ice.


A-Team

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Re: Epiq Sermia / West Greenland
« Reply #3 on: May 05, 2016, 01:47:52 PM »
Could this be an effect of wind coming off the glaciers on the slushy melange in front, some sort of standing wave for radar but not for visible?

nukefix

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Re: Epiq Sermia / West Greenland
« Reply #4 on: May 05, 2016, 04:02:26 PM »
Could this be an effect of wind coming off the glaciers on the slushy melange in front, some sort of standing wave for radar but not for visible?
I doubt it, it would need to modify the surface somehow for that to be possible.

I don't think this is so strange in the end, small chunks calve "all the time" so catching some in a set of wide images cannot be that rare...

Wipneus

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Re: Epiq Sermia / West Greenland
« Reply #5 on: May 13, 2016, 09:53:48 AM »
I though I remembered the name:

Lüthi, M. P. and Vieli, A.: Multi-method observation and analysis of a tsunami caused by glacier calving, The Cryosphere, 10, 995-1002, doi:10.5194/tc-10-995-2016, 2016

Abstract:

Quote
Glacier calving can cause violent tsunami waves which, upon landfall, can cause severe destruction. Here we present data acquired during a calving event from Eqip Sermia, an ocean-terminating glacier in west Greenland. During an exceptionally well-documented event, the collapse of 9  ×  105 m3 ice from a 200 m high ice cliff caused a tsunami wave of 50 m height, traveling at a speed of 25–33 m s−1. This wave was filmed from a tour boat at 800 m distance from the calving face, and simultaneously measured with a terrestrial radar interferometer and a tide gauge. Tsunami wave run-up height on the steep opposite shore at a distance of 4 km was 10–15 m, destroying infrastructure and eroding old vegetation. These observations indicate that such high tsunami waves are a recent phenomenon in the history of this glacier. Analysis of the data shows that only moderately bigger tsunami waves are to be expected in the future, even under rather extreme scenarios.

The event took place on 2 July 2014.

A description of the site:

Quote
Eqip Sermia (...) is a medium size
outlet glacier on the west coast of the Greenland Ice Sheet.
The  terminus  area  is  about  4 km  wide  and  terminus  flow
speed  was  about  3 m day-1 during  the  last  century,  corre-
sponding to a calving flux of 0.8 km3 a-1 (Bauer, 1968).
After a century of slowly varying terminus positions, a slow
retreat  and  acceleration  started  in  2000,  and  flow  veloci-
ties accelerated to 14 m day-1 in 2014 (Lüthi et al., 2016).
In  2014,  the  calving  front  reached  150–200 m  height  in
the northern terminus lobe. This high calving front formed
around  2012  and  induced  calving  events  that  lead  to  15 m
tsunami waves upon landfall which had not been observed
before,  and  which  destroyed  the  boat  landing  of  a  local
tourist operation.
« Last Edit: May 13, 2016, 03:45:38 PM by Wipneus »

Tor Bejnar

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Re: Epiq Sermia / West Greenland
« Reply #6 on: May 13, 2016, 03:16:14 PM »
from the quote, I presume "9  ×  105 m3"  is   9  ×  105 m3. (Edit:  after the fix, this note reads weirdly :-\  but I wouldn't have it any other way.  :))
« Last Edit: May 13, 2016, 04:17:21 PM by Tor Bejnar »
Arctic ice is healthy for children and other living things.

Wipneus

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Re: Epiq Sermia / West Greenland
« Reply #7 on: May 13, 2016, 03:46:16 PM »
from the quote, I presume "9  ×  105 m3"  is   9  ×  105 m3.

Yes, thanks, corrected.

Cate

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Re: Epiq Sermia / West Greenland
« Reply #8 on: June 25, 2016, 07:58:22 PM »
Article with videos, by Chris Mooney in the WP, on the tsunamis caused by calving at Epiq Sermia.

https://www.washingtonpost.com/news/energy-environment/wp/2016/06/23/this-melting-greenland-glacier-is-now-producing-terrifying-tsunamis/

Cate

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Re: Epiq Sermia / West Greenland
« Reply #9 on: July 24, 2016, 02:57:44 PM »
http://www.arctic.io/explorer/8/2016-07-23/9-N70.04547-W50.77511

Toggle from July 21-23 and in that little maze of fjord channels directly east of the big island (I think it's Epiq Sermia? or at least that vicinity) and notice two white patches that appear at the front edge of the glaciers--whoosh! Is it clouds? Or what's going on there, can anyone explain for a newbie please?

Tealight

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Re: Epiq Sermia / West Greenland
« Reply #10 on: July 24, 2016, 11:19:31 PM »
http://www.arctic.io/explorer/8/2016-07-23/9-N70.04547-W50.77511

Toggle from July 21-23 and in that little maze of fjord channels directly east of the big island (I think it's Epiq Sermia? or at least that vicinity) and notice two white patches that appear at the front edge of the glaciers--whoosh! Is it clouds? Or what's going on there, can anyone explain for a newbie please?

To me it looks like a typical calving event from a grounded glacier. The ice breaks away or falls off the front and leaves an ice debris field in the fjord. Jakobshavn does that all year round so its fjord is constantly filled with ice.

The Ryder Gletcher has a floating ice front so its calvings tend to just float away in one piece.
http://forum.arctic-sea-ice.net/index.php/topic,886.msg84447.html#msg84447
« Last Edit: July 24, 2016, 11:25:26 PM by Tealight »

Cate

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Re: Epiq Sermia / West Greenland
« Reply #11 on: July 25, 2016, 03:43:48 AM »
http://www.arctic.io/explorer/8/2016-07-23/9-N70.04547-W50.77511

Toggle from July 21-23 and in that little maze of fjord channels directly east of the big island (I think it's Epiq Sermia? or at least that vicinity) and notice two white patches that appear at the front edge of the glaciers--whoosh! Is it clouds? Or what's going on there, can anyone explain for a newbie please?

To me it looks like a typical calving event from a grounded glacier. The ice breaks away or falls off the front and leaves an ice debris field in the fjord. Jakobshavn does that all year round so its fjord is constantly filled with ice.

The Ryder Gletcher has a floating ice front so its calvings tend to just float away in one piece.
http://forum.arctic-sea-ice.net/index.php/topic,886.msg84447.html#msg84447

Cool, thank you so much. By the looks of all the debris, it would have been quite the sight to see.  I have to figure out how to get a closer look at it now. :)

Tealight

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Re: Epiq Sermia / West Greenland
« Reply #12 on: July 25, 2016, 09:36:45 PM »
...I have to figure out how to get a closer look at it now. :)

The best high-res images are from Landsat, Sentinel 1 and 2. If you want to find out more about them just use the search function. There are plenty of posts about how to get and work with them. Very popular with some members is http://www.polarview.aq/

Attached is a gif animation using S2A images at 10m resolution from the 21st and 24th July. The calving area was around 150-200m wide and 2000m long or 0.34km2. At MODIS resolution (250m) that might not even be a thin line.

Click image to animate

Cate

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Re: Epiq Sermia / West Greenland
« Reply #13 on: July 26, 2016, 01:23:53 AM »
...I have to figure out how to get a closer look at it now. :)

The best high-res images are from Landsat, Sentinel 1 and 2. If you want to find out more about them just use the search function. There are plenty of posts about how to get and work with them. Very popular with some members is http://www.polarview.aq/

Attached is a gif animation using S2A images at 10m resolution from the 21st and 24th July. The calving area was around 150-200m wide and 2000m long or 0.34km2. At MODIS resolution (250m) that might not even be a thin line.

Click image to animate

tealight, that animation is great---thank you so much for posting it. It certainly helps me to understand what I was looking at in the original link. I imagine a 2 km-long calving would have been quite something to watch---from a safe distance well out in the fjord, of course! I do appreciate your taking the time to give me a few pointers. Cheers!

Tealight

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Re: Epiq Sermia / West Greenland
« Reply #14 on: July 26, 2016, 05:40:09 PM »
tealight, that animation is great---thank you so much for posting it. It certainly helps me to understand what I was looking at in the original link. I imagine a 2 km-long calving would have been quite something to watch---from a safe distance well out in the fjord, of course! I do appreciate your taking the time to give me a few pointers. Cheers!

Your welcome. I automated most of the work and it took me maybe 5min of actual work to make this gif. I like the ice tsunami videos you posted and would love to ride a wave on a speedboat one day.