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Author Topic: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland  (Read 1200086 times)

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2050 on: May 17, 2019, 04:39:36 PM »
 You need to zoom in on this gif from hycom to see the impressive outburst of freshwater from Jakobshavn around the 11th
Looks like the granular ice in the channel is being finely ground, from sentinel


Tor Bejnar

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2051 on: May 17, 2019, 07:48:48 PM »
You need to zoom in on this gif from hycom to see the impressive outburst of freshwater from Jakobshavn around the 11th
For the casual viewer who is not certain where Jakobshavn Glacier is located (thanks to Wikipedia):
Arctic ice is healthy for children and other living things because "we cannot negotiate with the melting point of ice"

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2052 on: May 20, 2019, 02:40:39 PM »
Thanks Tor
Interesting image of standing waves out in Disko, my guess is turbulence in the ocean leading to evaporation where warmer waters are exposed.
http://ocean.dmi.dk/arctic/images/MODIS/Disko/20190519s01b.ASAR.jpg
I had a go at an animation, close up is too stacato could almost be random images the big picture's not much better

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2053 on: May 26, 2019, 01:19:47 PM »
Looks like a massive slump has taken place just before the bend of the southern branch, polarview


I made a gif which seized up on ezgif at 82%, probably did something stupid, it looks as if the flow from the east has grown wider whether this persists we'll have to wait, I fear not too long.
« Last Edit: May 27, 2019, 12:37:25 AM by johnm33 »

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2054 on: May 27, 2019, 10:18:49 PM »
polarview some changes from yesterday well worth a look difficult to be sure whats going on could be big, but could be just the quirks of angles from the radar images.
« Last Edit: May 28, 2019, 02:24:45 PM by johnm33 »

Grubbegrabben

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2055 on: May 28, 2019, 11:26:41 PM »
Interesting view on Sentinel Hub on west Greenland. That looks like a lot of water discharging downhill from melt ponds? I searched a bit but couldn't find quite so many melt river features even in the middle of summer (tbh a very sloppy search going back just a few years). That area has been quite warm some time now and it's starting to show.

Edit: Adjust gain to 0.7 and gamma to 1.3 if you follow the link to the sentinel image below. It seems embedded in the link but it doesn't work for me.

https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=68.50006707835485&lng=-49.755706787109375&zoom=11&preset=91_SWIR&layers=B01,B02,B03&maxcc=24&gain=0.7&gamma=1.3&time=2018-11-01%7C2019-05-27&atmFilter=&showDates=false&showImage

b_lumenkraft

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2056 on: May 29, 2019, 08:10:33 AM »
That looks like a lot of water discharging downhill from melt ponds?

Hey Grubbegrabben, i replied to your post in the Greenland melting thread.


johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2057 on: May 29, 2019, 08:06:02 PM »
Bit small, images from 9/22/27 may. 29:04 to 08:06


Looking at the northern side at/beyond the bend


more detail
Swapped animation
« Last Edit: June 09, 2019, 04:42:29 PM by johnm33 »

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2058 on: May 30, 2019, 11:44:13 AM »
A slightly longer view/ smaller file.

That looks ok all images from sentinel 2-29 may

Alphabet Hotel

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2059 on: May 30, 2019, 08:21:40 PM »
I converted that latest GIF to mp4 at 1 frame/sec and upscaled it. (I was having a hard time seeing what was happening.) It looks like the melt pond at the top center drained and there is a huge amount of water pouring from the glacier face in the last frame. I don't remember anything like this from earlier years, certainly not this early.

ffmpeg is available on Linux of course, and for Windows I used Chocolatey.
[ https://chocolatey.org/packages/ffmpeg ]
ffmpeg -r 1 -i giphy_jacob_20150530.gif -vf "scale=664:412" -pix_fmt yuv420p giphy_jacob_20150530.mp4

« Last Edit: May 30, 2019, 10:27:37 PM by Alphabet Hotel »

b_lumenkraft

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2060 on: May 30, 2019, 08:28:19 PM »
"The file isn’t compatible with QuickTime Player."  :'(

Alphabet Hotel

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2061 on: May 30, 2019, 10:28:50 PM »
"The file isn’t compatible with QuickTime Player."  :'(

I forgot to change the pixel format. I fixed it.

b_lumenkraft

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2062 on: May 31, 2019, 06:27:45 AM »
Thank you Alphabet Hotel. :)

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2063 on: June 07, 2019, 11:05:05 AM »
Thanks Alphabet Hotel, I'm computer illiterate so appreciate you making it clearer.
There continues to be powerful discharge from the main branch, images from polarview 06:06 06:05



On polarview when I look at the ice north of Jakbshavn it appears to be forming waves, flowing both directly towards the coast and also south towards the fjord. where it appears to be slumping, it's not nearly as alarming when I look at Sentinel.

Shared Humanity

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2064 on: June 08, 2019, 06:33:54 PM »
As the flow exits the fjord, is the light color of the water extending outwards all brash ice or is it also due to sediment?

Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2065 on: June 08, 2019, 07:47:41 PM »
Expect a very heavy calving next!!!!!
Have a ice day!

P-maker

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2066 on: June 08, 2019, 07:54:30 PM »
SH,
I believe you have just documented a phase change of water quality from this glacier. As far as I can recall, I have never seen a plume of sediments like that before. It is by all means a reflection of the heavy melt, which has plaqued the western slope of the Greenland Ice Sheet this year since April.

Shared Humanity

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2067 on: June 08, 2019, 08:02:00 PM »
SH,
I believe you have just documented a phase change of water quality from this glacier. As far as I can recall, I have never seen a plume of sediments like that before. It is by all means a reflection of the heavy melt, which has plaqued the western slope of the Greenland Ice Sheet this year since April.

Thank you.

gerontocrat

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2068 on: June 08, 2019, 08:12:43 PM »
SH,
I believe you have just documented a phase change of water quality from this glacier. As far as I can recall, I have never seen a plume of sediments like that before. It is by all means a reflection of the heavy melt, which has plagued the western slope of the Greenland Ice Sheet this year since April.

I attach:-
Cumulative melt days from http://nsidc.org/greenland-today/
Cumulative Surface Mass Balance (SMB) from http://polarportal.dk/en/greenland/surface-conditions/

They show that the West coast is having an unusual year -especially around Jakobshavn Isbræ
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2069 on: June 09, 2019, 03:25:03 AM »
Expect a very heavy calving next!!!!!

Looking at the sentinel data there was another significant calving event between june 4 and june 8.
An additional retreat of ~ 1 km.
That makes a retreat of ~ 3 km since may 2


Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2070 on: June 09, 2019, 10:54:06 AM »
Expect a very heavy calving next!!!!!

As promissed:

Have a ice day!

b_lumenkraft

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2071 on: June 09, 2019, 11:19:25 AM »
I hope they filmed it!

J Cartmill

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2072 on: June 09, 2019, 01:22:44 PM »
Looks like calving on both branches.

Stephan

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2073 on: June 09, 2019, 05:30:27 PM »
Expect a very heavy calving next!!!!!

As promissed:

How did you know? What were the signs to successfully predict it?
It is too late just to be concerned about Climate Change

Alphabet Hotel

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2074 on: June 09, 2019, 06:51:25 PM »
Sentinel Playground shows it happened between the 6th and the 8th. The false color image using b_lumenkraft's settings is interesting. You can see a blue border along the areas disturbed in the channel.

Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2075 on: June 09, 2019, 06:56:57 PM »
Expect a very heavy calving next!!!!!

As promissed:

How did you know? What were the signs to successfully predict it?

Like in any other business, even in glacier observation field, dirty tricks are being used. ;)
Have a ice day!

nanning

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2076 on: June 09, 2019, 07:40:56 PM »
@Stephan
I think it may have something to do with periodicity of calving or the changing speed of the glacier or a known period after some artifact? What suspence!
I doubt you are doing anything dirty Espen.
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gerontocrat

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2077 on: June 09, 2019, 08:05:31 PM »
Expect a very heavy calving next!!!!!
As promissed:
How did you know? What were the signs to successfully predict it?
Like in any other business, even in glacier observation field, dirty tricks are being used. ;)
A case of who you know, not what you know?

https://sea.mashable.com/science/3694/airborne-nasa-scientists-just-filmed-something-troubling-in-greenland
@NASA #IceBridge ✈ observed surface melt north of Jakobshavn 💧💧
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Shared Humanity

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2078 on: June 09, 2019, 08:11:08 PM »
@Stephan
I think it may have something to do with periodicity of calving or the changing speed of the glacier or a known period after some artifact? What suspence!
I doubt you are doing anything dirty Espen.

Espen has a close friend who hikes the glacier dropping small, remote controlled IED's into crevasses which Espen detonates by hitting ctrl F7.

Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2079 on: June 09, 2019, 08:41:01 PM »
@Stephan
I think it may have something to do with periodicity of calving or the changing speed of the glacier or a known period after some artifact? What suspence!
I doubt you are doing anything dirty Espen.

You are right, I am not doing doing anything real dirty, but only using the resourses that are available!??? And that is info, the "new" world power!
Have a ice day!

Tor Bejnar

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2080 on: June 09, 2019, 09:05:55 PM »
Expect a very heavy calving next!!!!!
As promissed:
Just don't promise us an ice-free Arctic Ocean! :o
Arctic ice is healthy for children and other living things because "we cannot negotiate with the melting point of ice"

Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2081 on: June 09, 2019, 09:10:11 PM »
Expect a very heavy calving next!!!!!
As promissed:
Just don't promise us an ice-free Arctic Ocean! :o

Not this or next year, but you will be very surprised when it happens, it will be be within days!
Have a ice day!

Stephan

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2082 on: June 09, 2019, 09:52:52 PM »
@Stephan
I think it may have something to do with periodicity of calving or the changing speed of the glacier or a known period after some artifact? What suspence!
I doubt you are doing anything dirty Espen.

Espen has a close friend who hikes the glacier dropping small, remote controlled IED's into crevasses which Espen detonates by hitting ctrl F7.
So I hope that Espen waits until his friend is in a safe distance before he presses the buttons... ;-)
« Last Edit: June 09, 2019, 10:03:52 PM by Stephan »
It is too late just to be concerned about Climate Change

lifeblack

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2083 on: June 11, 2019, 06:18:33 PM »
Sentinel Playground shows it happened between the 6th and the 8th. The false color image using b_lumenkraft's settings is interesting. You can see a blue border along the areas disturbed in the channel.

In Alphabet Hotel's picture, I see a decent-sized shadow from the calving face of the glacier...  Would it be possible to pixel-count and come up with a rough estimate of the height of the calving face?  I'm not sure what the exact sun angle is in the picture, or I'd try calculating it myself

b_lumenkraft

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2084 on: June 11, 2019, 06:35:32 PM »
Lifeblack, here is a website that can calculate such things. >> https://www.suncalc.org/#/69.1638,-49.7059,8.503333333333327/2017.06.23/16:00/25/0

Don't ask me how to work this thing though.  :-X

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2085 on: June 12, 2019, 09:39:55 AM »
Stunning image of winds in Disko 21:00 on 11:06


but take a look at the temp. bone dry air blowing down from the ice sheet!
https://earth.nullschool.net/#2019/06/11/2100Z/wind/surface/level/overlay=temp/orthographic=-51.09,69.04,3000/loc=-50.551,69.151

Alphabet Hotel

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2086 on: June 12, 2019, 05:53:13 PM »
There is some serious melting going on way upstream. The two images in this animation are from the 5th and the 12th. The latest one looks like a large river system has formed and is draining down into the glacier.

https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=69.20863520427898&lng=-48.41631226125173&zoom=12&preset=CUSTOM&layers=B01,B02,B03&maxcc=31&gain=1.0&gamma=1.0&time=2018-12-01%7C2019-06-12&atmFilter=&showDates=false&evalscript=cmV0dXJuIFtCOEEqMixCMDMqMSxCMDIqMV0%3D&showImage


lifeblack

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2087 on: June 12, 2019, 08:29:56 PM »
Lifeblack, here is a website that can calculate such things. >> https://www.suncalc.org/#/69.1638,-49.7059,8.503333333333327/2017.06.23/16:00/25/0

Don't ask me how to work this thing though.  :-X

So experimenting around with sentinel hub playground I discovered that although I could get the day, I couldn't figure out the precise image acquisition time...  However I was able to use the suncalc website to get the approximate sun azimuth angle by looking at the shadow direction. 
Net result, plus or minus about 5 meters, I get a calving face height of 48 meters on the left side where it runs more east-west, and a maximum height of about 95 meters at the center if all of my questionable assumptions hold up.  Does that sound roughly what might be expected?

b_lumenkraft

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2088 on: June 12, 2019, 08:59:34 PM »
Quote
If the depth is over 1000 m, the calving face would have to be higher than 100 m to be grounded. We found values of the calving face of up to 135 m using long range terrestrial laser scanner measurements in July 2007 [Schwalbe and Maas, 2009].

Link >> https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012JF002515

Though the hight of the glacier is variating somehow.

Quote
Simultaneously with the massive retreat of the frontal position of more than 15 km in the last decade, Jakobshavn Isbræ accelerated in summer from ~ 26 m/d in 2000 to 45 m/d in 2004 and thereby thinned at a rate of up to 15 m/yr.

nukefix

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2089 on: June 12, 2019, 10:38:39 PM »
So experimenting around with sentinel hub playground I discovered that although I could get the day, I couldn't figure out the precise image acquisition time...
That should be available here to the necessary degree:

https://sentinel.esa.int/web/sentinel/missions/sentinel-2/acquisition-plans

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2090 on: June 14, 2019, 11:03:14 AM »
With all the clear sky we have been seeing recently I couldn't resist putting together an animation of the last month's movements.

Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2091 on: June 14, 2019, 12:44:31 PM »
Surrounding Ice Retreat at Jakobshavn, since this is only a study about how much the ice on the rocks surrounding Jakobshavn Isbræ is affected by the climate changes, the glacier itself is masked, but watch the rocks marked with X, the timespan is only about 2½ year (September 2016 - June 2019), quite dramatic if you ask me?
Have a ice day!

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2092 on: June 14, 2019, 03:14:42 PM »
Espen,
It is especially dramatic as September image is from near (at) the end of the melting season (2016 has a higher snow/ice elevation) while the June image (2019) is from near the beginning of the melting season.
Arctic ice is healthy for children and other living things because "we cannot negotiate with the melting point of ice"

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2093 on: June 14, 2019, 03:23:15 PM »
Espen,
It is especially dramatic as September image is from near (at) the end of the melting season (2016 has a higher snow/ice elevation) while the June image (2019) is from near the beginning of the melting season.

Yes you right, thats why I picked the September image.
Have a ice day!

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2094 on: June 14, 2019, 07:09:44 PM »
The ice on the nw side is looking very vulnerable, small calving and some discharge into the bay on Polarview today, zoomable

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2095 on: June 14, 2019, 07:23:54 PM »
An unmasked view would also be nice to compare three years of the evolution of the calving front...
It is too late just to be concerned about Climate Change

Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2096 on: June 14, 2019, 10:38:17 PM »
An unmasked view would also be nice to compare three years of the evolution of the calving front...

Not realy since the the retreat of the glacier at both the northern and southern branch were further back in 2016.
Have a ice day!

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2097 on: June 15, 2019, 12:40:52 AM »
Espen,
It is especially dramatic as September image is from near (at) the end of the melting season (2016 has a higher snow/ice elevation) while the June image (2019) is from near the beginning of the melting season.

And note the ice that is left is becoming very thin you can allready see the contours of the rock underneath, so in a few years it will (forever) be different again!
Have a ice day!

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2098 on: June 17, 2019, 05:28:58 PM »
Another calving and huge discharge from the main branch Polarview