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Author Topic: Zachariae Isstrøm / Nioghalvfjerdsfjorden / NE Greenland  (Read 551317 times)

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #50 on: November 17, 2013, 03:54:59 PM »
Thank you Andreas and Espen, I attach below images from 2009 which show the calving front at that time as a step from thick glacier to thinner sea ice and icebergs (the DMI site only goes back to 2009 as far as I can tell)
http://ocean.dmi.dk/arctic/images/MODIS/Joekelbugt/20090901AQUA.jpg
http://ocean.dmi.dk/arctic/images/MODIS/Joekelbugt/200908301233.ASAR.
http://ocean.dmi.dk/arctic/images/MODIS/Joekelbugt/20090712TERR.jpg
The ASAR image picks that calving front out more clearly as a white line which shows glacier and tongue still hanging together a.f.a.i.c.t. What I find interesting in the radar image is that the image of 30.8. shows the structure of the sea ice which also can be seen in the visible image of 21.7. but not in the visible 1.9.
That, I guess is due to the radar penetrating snow cover, but how much more can it tell about the condition of the ice? I am thinking of the "darker" ice along Lambertland. I know I behave like a kid which follows every answer by a new question ::)
« Last Edit: November 17, 2013, 05:16:22 PM by Andreas T »

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #51 on: December 15, 2013, 05:39:49 PM »
I may just have overlooked this before but think for anybody wondering why this glacier is worth keeping an eye on, have a look at the bedrock elevation map in http://glacierchange.wordpress.com/2012/08/27/zachariae-isstrom-further-retreat-ne-greenland/
This made clear to me why Espen thinks that here is a major outlet for the Greenland Ice Sheet.

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #52 on: December 16, 2013, 01:04:32 AM »
I do not think  it coincidence that the fastest sea terminating glaciers on Greenland have low elevations of land between the interior sub-sea level Greenland.

Espen

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #53 on: March 04, 2014, 07:49:28 PM »
The guys from the North East is a back in town:

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #54 on: March 09, 2014, 08:46:35 PM »
First good image this season from Modis showing Zachariae Isstrøm and The 79 Gletscher, looking forward to many hours of studies, since it is the most interesting part of Greenland, in my opinion ;)
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sidd

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #55 on: March 10, 2014, 04:47:17 AM »
I used to be quite worried about Nioghalvfjerdsfjorden and NEGIS. But after staring at the Bamber(2013) bed data, i am more worried about Jacobshawn and Petermann because i see channels for seawater to penetrate to the heart from those two.

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #56 on: March 10, 2014, 09:13:17 PM »
Hi Sid,

I am still looking for visuel bed-data for both the Jøkelbugt Area ( Zachariae and 79th) and Dove Bugt (L. Ibstrup Bræ , Bredebræ and Storstrømmen), I believe we are in for some surprises.
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #57 on: March 11, 2014, 03:04:22 AM »
Profs. Bamber and Howat were kind enough to make the dataset available to me. I can do detail views or perspective, or contours, please see

http://membrane.com:/sidd/greenland-2013/

for some i have already done. Let me know what you need. I am travelling over the next 2-3 weeks, but i  will try to help as speedily as I may.

sidd

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #58 on: March 11, 2014, 09:10:06 AM »
Espen, does the bedrock map Mauri Pelto shows( link in my earlier post) not sufficient / doubtful?
 
Quote
A view of the basal topography from Joughin et al (2001) indicates that the acceleration occurs in the same area as the bed depth drops significantly below sea level 200 km from the ice front. The base of the glacier is 300-700 meters below sea level all the way to the ice front. The thickness at the grounding line is noted as 550-600 meters by Rignot et al (2001). The result is an ice flux at the grounding line of ZIS of some 11 cubic kilometers per year, this is much less than the 40+ cubic kilometers from Jakobshavn Isbrae and similar to the 12 cubic kilometers from Petermann Glacier.

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #59 on: March 11, 2014, 03:33:29 PM »
I may just have overlooked this before but think for anybody wondering why this glacier is worth keeping an eye on, have a look at the bedrock elevation map in http://glacierchange.wordpress.com/2012/08/27/zachariae-isstrom-further-retreat-ne-greenland/
This made clear to me why Espen thinks that here is a major outlet for the Greenland Ice Sheet.

I have, perhaps, another important reason why we should be concerned about many of the larger sea terminating glaciers in Greenland. We always use the term "bedrock" when describing the topography under these glaciers. I believe this is a potentially highly inaccurate description of the areas where these glaciers are grounded.

We know that the Humboldt Glacier releases large amounts of silt during its episodic upwellings. Bedrock should not, I believe, release so much silt during these periodic releases of melt water.

http://www.flickr.com/photos/greenpeaceusa09/3830848485/#

I suspect these relatively large yet low areas of elevation under the sea terminating glaciers are more likely to have the characteristics of glacial moraines, material that has been scoured from the interior of Greenland and deposited. The large moraines deposited across North America as the ice sheets retreated at the end of the last ice age are a mix of boulders, gravel, sand and other loose materials. Attached is a map of the major moraines in North America.

As seen on this topography map of Ohio, large ice sheets can deposit moraines with elevations of 1000 feet or more when they retreat. Aren't the ice sheets on Greenland thicker than the ice sheets that covered North America? If so the material scoured and deposited would likewise be larger.

http://www.dnr.state.oh.us/portals/10/pdf/sem_tone.pdf

The moraines are very prone to erosion and I think this could very well be the fate of these elevated areas that we call "bedrock". They are nothing of the sort. As melt water continues to find its way to the bottom of these large sea terminating glaciers, these elevated areas will erode and wash into the sea. This altered topography will reveal the true nature of the seas connections to the interior of Greenland, wide and shallow plains terminating in shallow estuaries as the rivers reach the sea.
« Last Edit: March 13, 2014, 09:02:15 PM by Shared Humanity »

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #60 on: March 11, 2014, 03:45:40 PM »
I have a lot of questions regarding current research on Greenland.

Does anyone have a map of the retreat of the Greenland ice sheet from previous warm periods? I seem to recall that the ice sheet retreated to the center of the top half of Greenland. Did the ice sheet edge line up with these elevations under the sea terminating glaciers? If so this would  support the idea these elevations are moraines.

Also, is there research about the nature of the seabed around Greenland? Are the surfaces of the seabed surrounding Greenland different where these sea terminating glaciers exist? It would seem we might be able to find deposits of loose material at these exit points for the major glaciers, boulders, gravel and other materials that washed into the sea as the glaciers retreated.

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #61 on: March 11, 2014, 04:24:42 PM »
When you consider the possibility that these relatively low elevations under the sea terminating glaciers are not bedrock but, in reality, loose materials deposited by the last major ice sheet retreat on Greenland and revisit the topography map under the Zachariae Isstrom Glacier provided above by Andreas T., the low lying areas nearest the sea begin to resemble a large river delta, evidence of ongoing erosion of the moraine deposits into the sea.

I've attached a landsat image of the Chesapeake Bay river deltas for comparison purposes.
« Last Edit: March 13, 2014, 08:57:35 PM by Shared Humanity »

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #62 on: March 13, 2014, 08:46:12 PM »
It is pretty clear I've either killed or mortally wounded this thread with my wildly speculative and grossly ill informed posts. Given the damage has already been done, I thought I would put one final bullet in the thread by asking a hopelessly naïve question.

Is it foolish to think that the behavior of sea terminating glaciers, rivers of ice, would mirror the behavior of the rivers lying, or would otherwise lie, deep beneath them? In other words, should we be surprised that a river of ice and the river beneath it would move rapidly through a deep gorge or canyon as it races to the sea? Likewise, shouldn't Humboldt Glacier move slowly across a broad plain just as a river might as it winds its way slowly to the sea.

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #63 on: March 13, 2014, 09:36:59 PM »
Having grown up in an area shaped by the debris of the last ice age (just north of the Alps) I often wondered how the ice produced those hills of gravel and sand. The way I would interpret that Zachariae map is that the trough under its lower part is produced by the scouring of the ice which most likely leaves loose sediment on the sea floor in front of it. That shows up as the higher elevation greens beyond the grounding line.
Rivers spread gravel into alluvial fans and may cut into it when they have sufficient gradient, but ice scours on a wide front and builds up deposits in front of it, that is what produced the lakes of southern Germany.
Speed of the ice flow is determined by gradient. The connection with the width of the flow is through availability of upstream material. A faster flowing Humboldt glacier would lower its gradient and slow itself down. I think what is able to change the present flow rates is the change in viscosity of the ice and the friction between ice and bedrock that warming and meltwater brings.

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #64 on: March 13, 2014, 10:03:15 PM »
Having grown up in an area shaped by the debris of the last ice age (just north of the Alps)
Ha! Me too. I'm currently sitting near the river Alz in Burgkirchen. Where are you from?

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #65 on: March 14, 2014, 10:37:51 AM »
You cannot have perfect weather everywhere I guess. Still through the clouds I think this first Landsat 8 image of the Zachariae icestream is of interest: the calving front is visible (retreated perhaps?) and very few "calvings".

(according to the meta data the sun elevation is 7.5 degrees)
« Last Edit: March 14, 2014, 11:01:02 AM by Wipneus »

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #66 on: March 14, 2014, 11:04:51 AM »
The 79N fjord image is even more difficult to read. Under magnification the calving front can be seen on the right (hint: there are 6 little islands buttressing the glacier there).

 

Espen

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #67 on: March 14, 2014, 04:23:06 PM »
Wipneus,

Great images, where did you get those images, I didnt know Landsat 8 (2014) got that far north already?
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Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #68 on: March 14, 2014, 06:22:03 PM »
Wipneus,

Great images, where did you get those images, I didn't know Landsat 8 (2014) got that far north already?

I get them here these days. As you see some images are available the next day. The coverage is spotty though, I have no luck yet with finding the pieces of the PII-2012 for instance even if they must be at a much lower latitude.

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #69 on: March 14, 2014, 09:59:16 PM »
Thanks Wipneus! ;)
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Stephen

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #70 on: March 16, 2014, 11:38:29 PM »
http://www.abc.net.au/news/2014-03-17/global-warming-melts-greenland-ice-sheet/5324848

"In a study published in the journal Nature Climate Change, researchers said a surge in temperature from 2003 had eased the brakes on a long "river" of ice that flows to the coast in north-eastern Greenland."

Any comment regarding the source paper for this news item?
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #71 on: March 17, 2014, 05:32:34 AM »
Zachariae Isstrøm is definitely on the move, not so much 79th Fjords. Zachariae even moved during the last dark season.
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #72 on: March 17, 2014, 07:44:36 AM »
"Zachariae Isstrøm is definitely on the move, not so much 79th Fjords. Zachariae even moved during the last dark season."

Right on. I attach Fig 4d and 4e from Khan(2014) doi:10.1038/NCLIMATE2161
see how ZI is still grounded unstable on retrograde bed but NG is already afloat from deepest point out to calving front.



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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #73 on: March 17, 2014, 06:11:32 PM »
http://www.abc.net.au/news/2014-03-17/global-warming-melts-greenland-ice-sheet/5324848

"In a study published in the journal Nature Climate Change, researchers said a surge in temperature from 2003 had eased the brakes on a long "river" of ice that flows to the coast in north-eastern Greenland."

Any comment regarding the source paper for this news item?

Another study of Zachariae Isstrøm etc. is just published in Copenhagen showing more or less the same. I now better understand the "Radio Silence" when I asked into the matter over the last couple of of years here in CPH, they wanted to publish the "secret" first?

But the fact is, the Jøkelbugt Area with Zachariae Isstrøm, 79 Fjord etc. will be one of the most interesting and important places to watch when talking about changes in the Arctic, as I have noted several times before. 
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #74 on: March 17, 2014, 06:25:12 PM »
An article ( in danish) with the new study made by DTU Space, Copenhagen:
http://www.dtu.dk/Nyheder/2014/03/Nu-smelter-den-nordligste-del-af-indlandsisen

« Last Edit: March 17, 2014, 07:18:29 PM by Espen »
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #76 on: March 18, 2014, 08:16:09 AM »
And here in English: http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2161.html
Thank you for that link Espen, all the others were behind a different paywall than I have access to.

PM me for help if anyone else cannot see it.
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #77 on: March 23, 2014, 08:57:19 AM »
Sun elevation is still low (11 degrees) but far better quality images on the 22nd.

(better resolution if you click those pictures)

Here is the calving front of Zachariae:

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #78 on: March 23, 2014, 08:59:46 AM »
And here 79N:

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #79 on: March 23, 2014, 09:39:14 AM »
And here a small animation of ice movements at Zachariae since end of melting season (September 24 2013) up to yesterday March 22 2014.
It is clear Zachariae is moving during the winter.

Please click on image to enlarge and start of animation!
« Last Edit: March 23, 2014, 09:44:39 AM by Espen »
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #80 on: March 23, 2014, 10:08:12 AM »
We can expect further calvings and retreat, 3 - 5 km from the calving front south of Kap Zachariae is ready to move.
« Last Edit: March 23, 2014, 10:13:18 AM by Espen »
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #81 on: March 23, 2014, 10:31:24 AM »
The red line is indicating where we will probably will see more calving or retreats in the near future:

Please click on image to enlarge!
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Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #82 on: March 23, 2014, 12:54:47 PM »
One thing I find interesting about those images is that the dark glacier surface and the exposed rock surfaces surrounding it show very little snowcover. Is that the result of wind blowing it away or does it just not get much precipitation up there?

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #83 on: March 23, 2014, 01:00:41 PM »
One thing I find interesting about those images is that the dark glacier surface and the exposed rock surfaces surrounding it show very little snowcover. Is that the result of wind blowing it away or does it just not get much precipitation up there?

This time of the year more likely the wind.
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #85 on: March 26, 2014, 08:10:30 PM »
I always focused on the Jøkelbugt area, because I believe it is the place that will show, something is completely wrong, and I am afraid we will soon find out, so please all interested; keep your eyes focused here and not so much the other trivial places! ;) 
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #86 on: March 26, 2014, 08:42:55 PM »
"But the increasing contribution from the very cold northeastern part of the ice sheet during the last seven to eight years is new and very surprising."

Not surprised, anyone with little interest could see that happen?
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #87 on: March 29, 2014, 06:45:40 PM »
Here are some relatively new images from Zachariae Isstrøm (DTU Space 2012) I believe seen from north of Nørreland towards Lambert Land and Kap Zachariae:

More or less the same scenery we see at Jakobshavn.
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #88 on: March 29, 2014, 06:51:56 PM »
And one more (DTU Space 2012), in the clean Sunday dress ;)
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #89 on: March 30, 2014, 03:08:21 PM »
Thanks Espen. Amazing photos.  I assume you've seen Chasing Ice? Hard to know the scale, but that's a (small?) melt pond on the right?  normal for March? Cheers

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #90 on: March 30, 2014, 04:54:46 PM »
Here are some relatively new images from Zachariae Isstrøm (DTU Space 2012) I believe seen from north of Nørreland towards Lambert Land and Kap Zachariae:

More or less the same scenery we see at Jakobshavn.

Has the surface of this glacier always been so dark or has surface melt darkened it over time which would cause higher surface albedo and melt?

I also am fascinated by the face of the tabular icebergs. There are black streaks that run deep into the glacier exactly where the surface would suggest a large amount of melt. Is this what I am seeing? Are these vestiges of past moulins or at least evidence of surface melt making its way to the base of the glacier prior to calving??

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #91 on: April 05, 2014, 03:03:18 PM »
Here is an image taken on a flight from Norske Øer towards Lambert Land, the previous tongue of Zachariae Isstrøm is seen to the right. Image: DTU Space.
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #92 on: April 05, 2014, 03:51:41 PM »
Do you know the date of this image Espen?

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #93 on: April 05, 2014, 06:15:28 PM »
Wipneus,

Yes I do it was taken on September 1 2012, so a bit old :(
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #94 on: April 07, 2014, 07:07:14 PM »
Using Wipneus talents in imaging and with the help from Landsat 1.

The image show the big changes at Zachariae Isstrøm since 1976.

The red shaded area marked on the glacier has disappeared since 1976.
it means that at least 200 km2 of the glacier has disappeared and is now open sea at the end of the melt season.

Click on image to enlarge!
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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #95 on: April 07, 2014, 10:43:08 PM »
Thanks Espen, that's great. I don't suppose the red lines represent the yearly retreat ?

i am back home, and i shall try post some bedrock and ice elevation detail after i catch my breath.

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #96 on: April 08, 2014, 04:58:01 AM »
Sidd,

No that is the total retreat since 1976.
Have a ice day!

sidd

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #97 on: April 12, 2014, 06:36:14 PM »
Here is first cut at ice surface contours for NE GRIS
i will add labels on the contours, but for now, bear in mind they are spaced 100 m apart. Color scheme is horrible, and lines are too thick, will fix. Thought you might like to see some rushes.

will also do bedrock as time allows. Also there is a new ice surface dataset from Viet Helm for both GRIS and AIS, which i have not yet had the time to look at.

sidd

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #98 on: April 12, 2014, 06:37:29 PM »
Didnt attach the image in the last post


Espen

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #99 on: April 12, 2014, 06:53:36 PM »
Against the odds that is how I see the area too ;), looking forward to some more details. :D

Especially the bedrock details.
« Last Edit: April 12, 2014, 07:01:53 PM by Espen »
Have a ice day!