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Author Topic: Petermann Gletscher / Petermann Fjord / North West Greenland  (Read 125113 times)

Jmo

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Re: Petermann Gletscher / North West Greenland
« Reply #50 on: August 19, 2013, 06:54:32 AM »
Espen - that's interesting.  So those two pieces of ice near the seemingly unchanged terminal face were pushed into the fiord on the wind?

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #51 on: August 19, 2013, 07:28:45 AM »
Jmo;

When you study the images carefully you will notice something is missing.
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Phil.

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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #53 on: August 20, 2013, 12:53:57 PM »
Another fringe calving seems to be underway:
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #54 on: August 20, 2013, 02:00:08 PM »
Now it is clear a fringe calving happened, and I believe more is coming along those fissures I reported earlier this month

Approx. 5 km2 gone since July

https://forum.arctic-sea-ice.net/index.php/topic,53.msg11365.html#msg11365  :

« Last Edit: August 20, 2013, 02:27:54 PM by Espen »
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #55 on: August 20, 2013, 02:53:27 PM »
A little more info:

Please click on image to enlarge:
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Shared Humanity

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Re: Petermann Gletscher / North West Greenland
« Reply #56 on: August 20, 2013, 04:22:20 PM »
A little more info:

Please click on image to enlarge:

I have no understanding of the way glaciers behave.

Could this fringe calving which causes this glacier face to recede to match the rest of the glacier front (perhaps this fringe calving would actually cause this area to recede past the bulk of the glacier face) set up Peterman for the next big calving across the center of the glacier?

ghoti

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Re: Petermann Gletscher / North West Greenland
« Reply #57 on: August 20, 2013, 05:58:15 PM »
There wouldn't by any chance still be a camera (from "chasing ice") still operating and pointing at the calving front of the glacier would there? That would be too good to be true.

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #58 on: August 20, 2013, 07:48:39 PM »
Shared Humanity,

I would not be surprised to see another small calving at where the second fissure was, even before this meltseason is over.

Ghoti,

That camera from "chasing ice" I believe was installed at Jakobshavn Glacier.
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #59 on: August 20, 2013, 08:25:38 PM »
Petermann August 20 2013:

Click on image to start animation.

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Phil.

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Re: Petermann Gletscher / North West Greenland
« Reply #60 on: August 22, 2013, 12:21:51 PM »
Shared Humanity,

I would not be surprised to see another small calving at where the second fissure was, even before this meltseason is over.


It looks like another small piece broke away yesterday.

jdallen

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Re: Petermann Gletscher / North West Greenland
« Reply #61 on: August 31, 2013, 11:15:08 PM »
Greetings all;

New  poster on this thread.  Would anyone care to expound on what implications the mid-Greenland canyon may have on movement of the Petermann Glacier?

Any sense if, with increasing melt, we might actually see sub-glacial flow of melt water out of the channel?

Is it possible some of the changes we are seeing over time might already be driven by meltwater flow?
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #62 on: August 31, 2013, 11:55:46 PM »
Greetings all;

New  poster on this thread.  Would anyone care to expound on what implications the mid-Greenland canyon may have on movement of the Petermann Glacier?

Any sense if, with increasing melt, we might actually see sub-glacial flow of melt water out of the channel?

Is it possible some of the changes we are seeing over time might already be driven by meltwater flow?

No immediate since it has always been there, but yes, there are melt water channels placed inside Petermann Glacier already, that became a fact a few years ago in a scientific report.

I myself believe the these melt water channels have an important role in the disintegration we see with many glaciers connected to massive ice sheets like eg. GIS.

And I believe these melt water channels were seen  at the recent massive calving at Helheim Glacier on July 24 2013 and onwards, Helheim actually lost about 25% of all glacier ice lost in the period 1972 - 2013 (included), they can be seen here:
 https://forum.arctic-sea-ice.net/index.php/topic,553.msg14149.html#msg14149
please also watch the video in the same thread, the image is captured from that video
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Laurent

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Re: Petermann Gletscher / North West Greenland
« Reply #63 on: September 01, 2013, 10:38:26 AM »
Petermann will collect the melt water from a very very large area, Jakobshawn collecting area looks small compare to it !

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #64 on: September 04, 2013, 04:12:05 PM »
Between August 19 and 28 2013 a small piece of ice 0.8 x 1.3 = 1.04 km2 took of from Petermann Glaciers left flank.

Please click on image to enlarge a start animation!
« Last Edit: September 04, 2013, 05:48:58 PM by Espen »
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #65 on: September 13, 2013, 04:24:39 PM »
Nice sunny day at Petermann Fjord, it almost looks like Petermann had some "regrowth" :)
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Andreas T

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Re: Petermann Gletscher / North West Greenland
« Reply #66 on: September 14, 2013, 05:17:51 PM »
Sorry, this might belong into the stupid questions topic, but where can I find the picture on modis? Is it possible that there is a mistake in the date the picture was taken? With the sun down the glacier the edge is clearly identified, but surely it can't have moved several km since August?

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #67 on: September 14, 2013, 05:27:14 PM »
Sorry, this might belong into the stupid questions topic, but where can I find the picture on modis? Is it possible that there is a mistake in the date the picture was taken? With the sun down the glacier the edge is clearly identified, but surely it can't have moved several km since August?


Here is a Modis link for the same date, showing the "regrowth" ( it is sea ice packed nicely up against the PG calving front)

http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013256190000-2013256190500.250m.jpg
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Andreas T

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Re: Petermann Gletscher / North West Greenland
« Reply #68 on: September 14, 2013, 05:52:46 PM »
Thanks Espen, I shouldn't have doubted you (or have payed more attention to the smiley) :-[  I misread the band of open water for a shadow. The slight difference in colour between the sea ice and the glacier in the high res image shows you are right!

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #69 on: September 14, 2013, 06:03:16 PM »
That is OK Andreas, nice we had this solved before someone jumped on it! ::)
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #70 on: September 18, 2013, 12:05:48 PM »
As reported earlier this season, there is a fissure of Kap Bemerton (Petermann Fjord).
As you can see from this animation below a glacier is a dynamic place, in the period between June 12 and September 10 this year or ~3 months, the glacier moved ~ 300 meters or at a speed about 1.2 km per year.
The size of the fissure did not change much though.
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #71 on: October 07, 2013, 12:23:06 PM »
It is now time to say Good Winter to Petermann Glacier, at least in when it comes to  Modis :-\
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Andreas T

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Re: Petermann Glacier/North West Greenland
« Reply #72 on: November 18, 2013, 02:32:23 AM »
Checking out Landsat I stumbled over a fissure I never noticed before, although it is pretty far from the present calving front of Petermann Glestcher (aprox. 65 km). The fissure is located of Kap Bemerton and opposite Porsild Glestcher, and it is about 5 km in length, it may be a thing to watch?

Click on image to enlarge!

Trying to learn more about ASAR images, I think that fissure can be seen in April 2012
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201204010003.ASAR.jpg
sorry if that just makes the wait for the sentinel2 satellite an annoyingly long time :(
My interpretation would be that the radar picks out changes in depth (from satellite) and therefore shows up fissures like the one where the future PII-2012 will seperate 3 months later.

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #73 on: March 02, 2014, 07:24:14 PM »
First image from Petermann this season, it is an ASAR image from DMI:

Please click on image to enlarge!
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #74 on: March 02, 2014, 07:49:42 PM »
The New ASAR images from DMI is pretty good calving predicting tool I believe.
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #75 on: March 07, 2014, 08:45:35 PM »
First image from our friend Petermann courtesy of Modis:

« Last Edit: March 08, 2014, 08:51:58 AM by Espen »
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #76 on: March 07, 2014, 08:46:54 PM »
Now it is spring! ;)
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #77 on: March 08, 2014, 09:00:21 PM »
There seems to be loads of snow on top of Petermann this season:
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Shared Humanity

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Re: Petermann Gletscher / North West Greenland
« Reply #78 on: March 08, 2014, 10:28:42 PM »
There seems to be loads of snow on top of Petermann this season:

Is this net good or bad? Higher albedo may slow this years melt but, if the snow fell early last fall, the increased insulation may have discouraged ice thickening.

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #79 on: March 08, 2014, 11:09:57 PM »
I don't think more snow cover  makes a difference, it is more important what happening under and in the the glacier, and I don't expect another calving this season, unless it a a very big one!
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crandles

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Re: Petermann Gletscher / North West Greenland
« Reply #80 on: March 08, 2014, 11:31:36 PM »
I don't think more snow cover  makes a difference, it is more important what happening under and in the the glacier, and I don't expect another calving this season, unless it a a very big one!

I suspect SH is thinking about good or bad for arctic sea ice, as the glacier is obviously above equilibrium thickness so "increased insulation may have discouraged ice thickening" doesn't make sense unless talking about sea ice.

Shared Humanity

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Re: Petermann Gletscher / North West Greenland
« Reply #81 on: March 09, 2014, 12:16:58 AM »
I don't think more snow cover  makes a difference, it is more important what happening under and in the the glacier, and I don't expect another calving this season, unless it a a very big one!

I suspect SH is thinking about good or bad for arctic sea ice, as the glacier is obviously above equilibrium thickness so "increased insulation may have discouraged ice thickening" doesn't make sense unless talking about sea ice.

Yes, thank you. I meant for sea ice.

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #82 on: March 09, 2014, 09:43:04 AM »
The only serious fissure to be seen at Petermann Gletscher is at Kap Bemerton, aprox. 30 km from the present calving front, although there are some small fissures at Faith Gletscher.
« Last Edit: March 09, 2014, 09:49:19 AM by Espen »
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Wipneus

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Re: Petermann Gletscher / North West Greenland
« Reply #83 on: March 14, 2014, 09:36:51 AM »
First Landsat 8 image of the season. Cloud free, but the low sun elevation (5 degrees) makes the image somewhat lacking brilliance and detail.

Attached an overview in 30 m resolution. I will add an 15 m cut of the calving front. I am open to suggestions for other details, comparisons with autumn 2013 and details to watch this season.

(you must click the pic for full resolution images)

Wipneus

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Re: Petermann Gletscher / North West Greenland
« Reply #84 on: March 14, 2014, 09:40:34 AM »
Detail of the previous image but in the highest resolution.

(assuming that you do click the picture)

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #85 on: March 18, 2014, 08:17:03 PM »
Fantastic images, Wipneus, in 2 months time we will have the Sentinel-1 images too! ;)
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Wipneus

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Re: Petermann Gletscher / North West Greenland
« Reply #86 on: March 19, 2014, 06:45:23 AM »
Talking about what is  possible with the Sentinel-1 :
This ‘interferogram’ shows Petermann Glacier grinding towards the sea along the northwestern coast of Greenland. Two Radarsat-2 TOPS images acquired 24 days apart were used to generate it. Radarsat-2 was programmed specially by MDA to work in an experimental imaging mode called Terrain Observation by Progressive Scans (TOPS) in azimuth  to match the way ESA’s Sentinel-1 will image Earth.

Synthetic Aperture Radar Interferometry – or InSAR – is a technique where two or more satellite radar images acquired over the same area are combined to detect large-scale surface changes. Small changes on the ground cause changes in the radar signal phase and lead to rainbow-coloured fringes in the interferogram.

This image shows some stationary and relatively slowly moving features, as well as some large areas of much faster moving ice. The interferometric fringes are widely spaced in the stationary areas and closer together in the centre of the glacier where the ice is moving much faster.



Andreas T

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Re: Petermann Gletscher / North West Greenland
« Reply #87 on: March 19, 2014, 08:57:45 AM »
Thanks for another great image. At what time of the year was this taken and is there a scale for interference fringes / altitude change?

Laurent

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Re: Petermann Gletscher / North West Greenland
« Reply #88 on: March 19, 2014, 09:58:52 AM »
There is something I do not understand, if I read well, they say that the colored parts are the ones that move faster...but how can it be that the interior move and not the exit (Petermann glacier) ?

TerryM

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Re: Petermann Gletscher / North West Greenland
« Reply #89 on: March 19, 2014, 10:49:33 AM »
WOW! simply WOW!


Terry

Wipneus

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Re: Petermann Gletscher / North West Greenland
« Reply #90 on: March 19, 2014, 10:54:32 AM »
Thanks for another great image. At what time of the year was this taken and is there a scale for interference fringes / altitude change?

I don't know, the image just says released 17/03/2014. But the description indicates it is captured "recently" :

So that users are fully prepared for the images Sentinel-1A delivers, Canada’s Radarsat-2 was recently programmed by MacDonald, Dettweiler & Associates to scan Earth’s surface using the same novel ‘interferometric’ wide-swath mode technique as Sentinel-1. Consequently, a suite of images was acquired over various sites.


Wipneus

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Re: Petermann Gletscher / North West Greenland
« Reply #91 on: March 19, 2014, 10:58:17 AM »
There is something I do not understand, if I read well, they say that the colored parts are the ones that move faster...but how can it be that the interior move and not the exit (Petermann glacier) ?

My understanding is that large distances between colored bands indicate slower speed. As speed increases the colors come closer and closer together, until they appear no longer separated and blend into the grey. That is why the glacier is grey and the ice covered land has al the colors.

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #92 on: March 19, 2014, 10:02:38 PM »
It is interesting to see how far inside the flow of ice begins, it is at least the length what we regard as the fjord.
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Andreas T

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Re: Petermann Gletscher / North West Greenland
« Reply #93 on: March 20, 2014, 09:05:43 AM »
As I understand it the image shows a change in surface elevation. Flow of the ice can of course occur where that surface has a downward gradient but gradient and elevation does not change over time. My question about the timing of the image was therefore about whether this is showing a seasonal change in the ice. Clearly this is only the beginning of some very interesting and useful data. Getting this information over several seasons will show where the ice is getting thinner with amazing detail and coverage.

Shared Humanity

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Re: Petermann Gletscher / North West Greenland
« Reply #94 on: March 20, 2014, 04:31:50 PM »
OK.....stupid question.

Could the capture of surface changes on the ground be finding both evidence of movement but also melt?

icefest

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Re: Petermann Gletscher / North West Greenland
« Reply #95 on: March 20, 2014, 10:23:33 PM »
I'm not sure about whether elevation changes will differentiate movement and melt, but depending of radar wavelength it should be able to detect surface water vs ice.

Please comment if you know if this is false.
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Andreas T

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Re: Petermann Gletscher / North West Greenland
« Reply #96 on: March 21, 2014, 01:01:35 AM »
I found the answer to one of my questions here https://earth.esa.int/documents/10174/134665/S1-TN-ESA-SY-0452_RSAT_TOPS_InSAR_Scenes_Report
The images on which the interferogram is based were taken on 11.4.2013 and 5.5.2013.
A frequency of 5.4 Gigahertz would mean 2.8cm change in height for each line (my guess, the esa document doesn't seem to give that information)
« Last Edit: March 21, 2014, 09:10:47 AM by Andreas T »

Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #97 on: March 21, 2014, 07:11:46 PM »
What I meant with the ice flow from deep inside the GIS is better seen within the red line
The same is seen at Jakobshavn, and it is a indicator where  the glacier is heading in the future:
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #98 on: March 23, 2014, 04:45:40 PM »
Here is a "new" images compiled of very old Danish aerial images, and long before several calvings:

Please click on image to enlarge.
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Espen

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Re: Petermann Gletscher / North West Greenland
« Reply #99 on: March 23, 2014, 05:29:52 PM »
Here is another one of the major glaciers feeding Petermann Gletscher, this time Sigurd Berg Gletscher:

Please click on image to enlarge.
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