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Author Topic: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland  (Read 867728 times)

Stephan

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2150 on: April 09, 2020, 08:45:13 PM »
Thank you grixm - it's amazing how fast the things are starting at Jakobshavn Isbræ.
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Stumbi

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2151 on: April 23, 2020, 12:36:44 AM »
There is a lot of Melange free water in the Ilulissat Isfjord and some of the blocking icebergs at the mouth seem to be on the move
(Sorry still unable to produce a GIF, but you can check on worldview or sentinel playground, good weather recently
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oren

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2152 on: April 23, 2020, 02:17:48 AM »
Stumbi, maybe the online GIF maker would help?
https://ezgif.com/maker

Stumbi

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2153 on: April 25, 2020, 02:18:11 PM »
First try to make a gif.....
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oren

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2154 on: April 25, 2020, 02:28:20 PM »
First try to make a gif.....
Well done Stumbi  8)


grixm

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2156 on: April 29, 2020, 10:34:01 PM »
Another calving between April 27th and now




johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2157 on: May 10, 2020, 10:21:24 AM »
Full flood, some retreat east on the north front and a large calving on the glacier proper, nothing left of the blockages so the summer season begins.

from polarview
+ previous image From EO [5th i think]
« Last Edit: May 10, 2020, 10:31:13 AM by johnm33 »

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2158 on: May 16, 2020, 03:32:57 PM »
Cloud free from EO

grixm

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2159 on: May 22, 2020, 09:21:30 PM »
More calvings on both fronts

Stephan

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2160 on: May 23, 2020, 08:18:13 AM »
On which dates were the two pictures you used for that gif taken?
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Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2161 on: May 24, 2020, 01:33:00 PM »
Jakobshavn is pretty active this spring?
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Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2162 on: June 01, 2020, 03:34:50 PM »
A busy month is coming to an end:
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Stephan

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2163 on: June 01, 2020, 04:36:28 PM »
Hi Espen,
thank you for keeping us up-to-date. To be able to put the multiple calvings into context, has it been an unusually busy month? How far upstream are the two calving fronts in the main trunk and the northern branch compared to earlier years?
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Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2164 on: June 01, 2020, 04:56:17 PM »
Hi Stephan,

The southern branch is unusually deep this time of the season, compared to all years I have records of.
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johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2165 on: June 17, 2020, 11:15:03 PM »
Quite a flood considering we're so far from peak tides. polarview
+24hrs
« Last Edit: June 18, 2020, 11:10:38 AM by johnm33 »

Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2166 on: June 18, 2020, 10:10:12 AM »
Jakobshavn Isbræ
Very active this season but still far away from where it was August 16 2015.

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2167 on: June 30, 2020, 09:36:43 PM »
There's been a calving event. Sentinel does not have images up, but it's obvious even at this low resolution.



Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2168 on: July 01, 2020, 08:51:35 AM »
As reported earlier by AH Jakobshavn did a late June calving:

Please click on image to animate!
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johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2169 on: July 01, 2020, 05:05:45 PM »
Thanks Espen. The water out in Disko has been around 5/6C for days so with any tidal exchange plenty of melt opportunities. You wait for days then 3 polarveiw images at once[ish], the latest shows calving continues and the overturning wave to the north side of the south branch appears to be collapsing. Looking south some of the ice streams are becoming more defined, and upstream the 'circular feature' is more manifestly terraced suggesting to me that it sits in water and some deep  bass notes are permeating the ice. The link is to the variable image from earlier today.

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2170 on: July 14, 2020, 01:43:34 PM »
Link to variable image from polarview
The north side of the south stream where normally there's a standing wave appears to have calved, if thats the case it's new to me.

blumenkraft

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2171 on: July 14, 2020, 02:28:21 PM »
Thanks, John for having an eye on it!

Here's as a GIF.
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johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2172 on: July 18, 2020, 09:59:00 AM »
Very clear image from Sentinel yesterday looks like a logjam at the mouth of the fjord backing up to the calving fronts, maybe the tides will get it all moving in a couple of days?

NotaDenier

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2173 on: July 25, 2020, 01:46:07 AM »
Minor calfing. The north side of the south branch looks a little precarious.

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2174 on: July 27, 2020, 10:47:18 AM »
Very cloudy, has it rained? latest image from sentinel shows the logjam in the fjord breaking out.
 

and an earlier image showing two small calvings and perhaps the start of the breakout.

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2175 on: July 29, 2020, 08:43:59 PM »
Another image from Polarveiw showing calving and some accelerated loss from beneath the glacier[?]

Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2176 on: July 31, 2020, 08:41:46 AM »
Sermeq Kujalleq aka Jakobshavn Isbræ in Rock and roll mood:

Please click on image to animate!
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sidd

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2177 on: July 31, 2020, 08:55:03 AM »
Espen never sleeps ! that's awesome, kilometer collapse and retreat.

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NotaDenier

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2178 on: July 31, 2020, 07:37:04 PM »
Clear day today.

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2179 on: July 31, 2020, 09:06:31 PM »
 A number of @ 500m monsters there enough to block the exit, lets see if any get caught on the next cill where one of the recent giants appears stalled.

Tor Bejnar

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2180 on: July 31, 2020, 09:07:19 PM »
Great GIF, NotaDenier!

Between those two frames, the glacier advanced 1 unit of distance and calved ~6.5 units of distance (for a net 5.5 units retreat).  What I mean is, the glacier isn't just sitting there taking punches, but points on the (intact part of the) glacier are advancing at a brisk pace, with retreat happening, generally (and in your GIF), faster.
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RoxTheGeologist

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2181 on: August 01, 2020, 12:38:55 AM »

How high is the snout of the glacier now - do we have any idea?


sidd

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2182 on: August 01, 2020, 06:56:09 AM »
I think people have tried that by getting the sun angle from the time the image was made and then estimating the height of ice face from the size of the shadow. I dont know how successful they were ...

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johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2183 on: August 01, 2020, 11:44:29 AM »
There's a cill of sorts thereabouts, so maybe 100m+?

oren

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2184 on: August 01, 2020, 07:59:13 PM »
John, I believe it is spelled "sill".

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2185 on: August 01, 2020, 09:36:10 PM »
Maybe "Noun. cill (plural cills) Alternative form of sill (“underwater horizontal member which forms the base of a lock gate on a canal or river”)" i'm just a stubborn old git, but yes like asked morphing to axed i've not iced the drift.
 I wonder if the breakout/calving was related to the huge bergs causing a logjam by the sill, i've stated upstream that my guess is these giants formed in the deep ravines of the fjord and are being released by ingress of seawater, which in conjunction with tidal flexing, is slowly releasing them to the ice stream. Interesting that despite some big calvings there's been no great outburst of freshwater into Disko yet, if that doesn't change we may see a deep freeze set in among the melange of the outer fjord.

oren

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2186 on: August 01, 2020, 11:13:02 PM »
I think the glacier is around 1km tall at the front with around 100 meters above the water. Not sure.
In any case I think normal calving has the icebergs capsize (no tabular bergs at JH), so their height and depth when trying to float away should be much lower.
« Last Edit: August 02, 2020, 10:28:12 PM by oren »

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2187 on: August 02, 2020, 09:49:31 PM »
I tried doing a height estimation on the front once before, but I forget where I obtained the sun angle at the time the image was taken.  The answer I got (80 meters) was pretty reasonable.  I'd be interested in trying it again, since I think the longest shadows are right at where I think the glacier is thickest.

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2188 on: August 03, 2020, 10:27:26 AM »
Is the grounding line (GL) close to the retrograde-part of the channel yet? My impression is that the GL is close or at the calving front in normal conditions. It's difficult to image the position of the GL from space at Jakobshaven but perhaps local cameras etc. are doing it in real time?

NotaDenier

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2189 on: August 12, 2020, 04:13:12 AM »
All’s quiet on the jakobshavn front.

The third and tenth of August. Interesting how the bergs aren’t really moving.

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2190 on: August 12, 2020, 08:50:22 AM »
I wonder if the lack of movement indicates that the area behind the previous sill is simply filled with melange?

ArcTickTock

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2191 on: Today at 02:15:20 AM »
I am new here, just post in the Melting Season thread.

I have a question, much news was made in recent years about Jacobshavn reversing course and advancing instead of retreating but looking at the satellite images now the calving fronts do not look very far from their furthest retreat?  Has the advance stalled?