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Author Topic: Zachariae Isstrøm / Nioghalvfjerdsfjorden / NE Greenland  (Read 370959 times)

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #700 on: July 16, 2016, 09:08:46 AM »
Several calvings have broken, toppled over.

johnm33

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #701 on: July 23, 2016, 12:01:59 PM »
Just upstream from Z. any ideas what the waves/stripes are about

visible on http://go.nasa.gov/2ahxHdB too

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #702 on: July 23, 2016, 12:23:09 PM »
These features are also seen in 2015 and 2014, less in 2013 when there was less melt exposing the ice. That means they are in the ice or firn layer and seem to be parallel to the direction of ice flow. Some melt ponds are alligned with them
http://go.nasa.gov/2a4YbvA

johnm33

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #703 on: July 24, 2016, 12:38:52 AM »
Looking at http://nholschuh.com/glaciers.html this image area is 20-30w and 78-80n

and this from polar view is between 78-9 n

so I'm thinking that perhaps this is the result of some sort of infrasonic resonance propagating back from the calving front in a softened semi liquid basal layer.
IF [bigif] that's right this monster is lubricated and ready to go.

iwantatr8

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #704 on: July 24, 2016, 07:13:32 AM »
...is the result of some sort of infrasonic resonance propagating back from the calving front in a softened semi liquid basal layer.
...

Er, No.

What you are looking at are the resultant flow features generated from the internal stresses associated with the changing velocity profile of a distinctly non-Newtonian fluid.

Look here http://www.cpom.ucl.ac.uk/csopr/iv/index.html?glacier_number=0&image_date=160414_160508#output
for details of how rapidly the flow velocity changes both across and along the direction of flow.

Then try a couple of free access papers on glacier flow.

https://www.researchgate.net/profile/Gudmundur_Gudmundsson/publication/252424512_Basal_flow_characteristics_of_a_non-linear_flow_sliding_frictionless_over_strongly_undulating_bedrock/links/00463537a060cd6757000000.pdf

http://www.cpom.org/research/jad-ag.pdf
 

johnm33

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #705 on: July 26, 2016, 01:10:18 PM »
"Er No" Well as interesting as those links were none of them suggested any mechanism for the formation of parallel corrugations aligned with flow. So I thought maybe I'd try to find a similar glacier, none exist so far as I can see, this is defined as a Piedmont in Wiki. but really it's not emerging from any mountains, and it's not gravity driven except in the sense that the pressure is caused by gravity. Then I came across this http://www.nature.com/ngeo/journal/v7/n6/fig_tab/ngeo2167_F1.html which shows that underlying the area which I think bears the imprint of some sort of resonant effect there is a large basin, more or less perfectly situated, I couldn't enhance it sufficiently to be confident and then by chance or design Andreas T put this link up on the season page. http://membrane.com/sidd/greenland-2013/Zachtrough/
Looking at that it seems at least possible that some seawater penetration happens,[ bearing in mind the tidal lake in N79] and if not then a reservoir of meltwater may have formed, such that when a calving event occurs sound/pressure waves propogate through the deep channel and resonate below the ice.
 It also helps to make sense of the arched bulge that shows up on the sentinel images.

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #706 on: July 26, 2016, 06:48:53 PM »
No Sentinel 2 image yet, but Sentinel 1A records a rather large calving event, now more at the center and to the north of the calving front.
Image scaled from 10 to 20m/pix for size.

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #707 on: July 27, 2016, 03:45:55 PM »
Landsat sequence day 205 in 2015 and day 208 in 2016. Pink line is the calving front in July 2015. The position of the front is similar except in the north where front was more retreated in 2015.

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #708 on: July 27, 2016, 05:29:45 PM »
"Er No" Well as interesting as those links were none of them suggested any mechanism for the formation of parallel corrugations aligned with flow. So I thought maybe I'd try to find a similar glacier, none exist so far as I can see, this is defined as a Piedmont in Wiki. but really it's not emerging from any mountains, and it's not gravity driven except in the sense that the pressure is caused by gravity. Then I came across this http://www.nature.com/ngeo/journal/v7/n6/fig_tab/ngeo2167_F1.html which shows that underlying the area which I think bears the imprint of some sort of resonant effect there is a large basin, more or less perfectly situated, I couldn't enhance it sufficiently to be confident and then by chance or design Andreas T put this link up on the season page. http://membrane.com/sidd/greenland-2013/Zachtrough/
Looking at that it seems at least possible that some seawater penetration happens,[ bearing in mind the tidal lake in N79] and if not then a reservoir of meltwater may have formed, such that when a calving event occurs sound/pressure waves propogate through the deep channel and resonate below the ice.
 It also helps to make sense of the arched bulge that shows up on the sentinel images.
You have not addressed the fact that I showed these parallel lines which you are attributing to a recent event present in previous years. Wipneus' animation shows that the undulations are found in the same place after a year, more clearly than the worldview images.
You seem to be too fond of exotic explanations to look at boring facts. What exactly would your infrasonic resonance do to the ice? it is very thick there and your hypothetical "semiliquid state" would make it flow into the sea very quickly.
Looking at some other S1A images of Greenland glaciers I think there are similar lines although not as clearly at regular spacing as those you show above. But then the geography of width and inclination of the glacier are fairly unique. Secondary flow patterns near the surface of the glacier responding and mutually reinforced by patterns in meltwater runoff and firn accumulation seem a perfectly plausible and sufficient explanation to me but I do not claim to have any in depth knowledge of glaciology.

johnm33

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #709 on: July 27, 2016, 10:29:19 PM »
If I implied it was due to a recent event, that was a mistake, it's just that although I've always followed this thread and had probably noticed these lines before I presume I thought these were just the same sort of lines normally seen in a flowing glacier. It's only seeing how similar they are, for the first time, that made me stop and think. Looking back to the first page of this topic[recommended] for clues about dates to look at the oldest sign so far is here http://www.arctic.io/explorer/6oN7g/2013-08-06/9-N78.62644-W23.28894 but they begin to develop more noticibly after the 20th.  Looking at this image there's a bottleneck beneath the bulging arch[on sentinel images] that stops it all sliding to the sea.

from http://membrane.com/sidd/greenland-2013/Zachtrough/
" What exactly would your infrasonic resonance do to the ice?" One thing I would expect is for these corrugations to move across the flow line, but on what time scale?

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #710 on: July 28, 2016, 08:09:07 PM »
The sea ice over the trough north of Ile de France has been loosened and broken when the movement was northward now the movement of ice further east has resumed its usual southward directionan and it will be interesting to see how the ice inside belgica bank will react, in previous years it didn't move south quickly but that usually happened later in the year.
The other thing I am going to watch out for is whether loss of this ice will make the ice inside the islands melt. The openings between the islands are quite narrow and in previous years like 2013 when there was open water at the calving front of Zachariae, this happened by melting ice not by drifting away.

johnm33

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #711 on: July 29, 2016, 03:48:55 PM »
Whatever this is it's extending north and south


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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #712 on: August 03, 2016, 10:41:45 PM »
Looks like a little bit more than wind motion here.  Aqua band.
FNORD

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #713 on: August 04, 2016, 09:38:15 PM »
break up in the iceberg filled sea ice south of Zachariae just a few days later than in 2013. This can get interesting.

Andreas Muenchow

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #714 on: August 05, 2016, 01:21:28 PM »
The German research icebreaker R/V Polarstern is working in this area right now, e.g.,

http://www.meereisportal.de/en/seaiceexpedition/where-is-polarstern.html

The focus is on glacier-ocean interactions both from a modern (physical oceanography) and ancient (geology, paleo-oceanography) perspective with groups from Germany, England, and the US all working together. Wish them luck to recover those moored sensors computers placed in shallow waters where ice bergs may wipe them off the bottom of the ocean. A Canadian technician I work with is aboard to help, but I have not heart from him for 2-weeks; even simple text-only e-mails can be hard to get off the ship at times ...
A Sailor in a Changing Climate
http://IcySeas.org

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #715 on: August 05, 2016, 03:16:23 PM »
Water temperatures reported at http://www.sailwx.info/shiptrack/shipposition.phtml?call=dblk  are as high as 2.6oC
is that typical for the North East Water polynya?
With the recent movement and possible opening of sea ice there my curiosity has been drawn to the sediment plumes south of Zachariae. With the work you have done in the area, Andreas, can you point us to information on where that comes from? is it carried from under the ice sheet or is it local sediment from coastal deposits?
« Last Edit: August 05, 2016, 05:15:40 PM by Andreas T »

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #716 on: August 06, 2016, 03:21:52 PM »
Looks like a little bit more than wind motion here.  Aqua band.

Indeed. Sentinel 2 images are not coming in when you need them but here is a pair of Landsat 8 images 30 hours apart. The calving is now concentrated in the northern half. There are some indications that this one is initiated not from the glacier but from breakup of the debris field in the south noted by Andreas.

Full resolution (15m/pix, but you must click to see that.

Dave55

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #717 on: August 08, 2016, 08:29:43 AM »
break up in the iceberg filled sea ice south of Zachariae just a few days later than in 2013. This can get interesting.

I don't have the time or tech skills to post imagery but just doing a scroll through MODIS imagery there is massive movement since August 1 and what looks like a big calving in the north. Looks like the the sea ice was acting as a big dam that has now been released.

I'm generally just a lurker here and enjoying reading the discussion and learning a lot but felt this little observation was worth noting.  Back to lurking again!

Iceismylife

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #718 on: August 08, 2016, 09:26:44 PM »
break up in the iceberg filled sea ice south of Zachariae just a few days later than in 2013. This can get interesting.

I don't have the time or tech skills to post imagery but just doing a scroll through MODIS imagery there is massive movement since August 1 and what looks like a big calving in the north. Looks like the the sea ice was acting as a big dam that has now been released.

I'm generally just a lurker here and enjoying reading the discussion and learning a lot but felt this little observation was worth noting.  Back to lurking again!
http://go.nasa.gov/2b1uwXZ
http://go.nasa.gov/2aPGlgD

just those two days was impressive.

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #719 on: August 09, 2016, 05:16:40 PM »
A Sentinel 2A image appeared of the 6th of August, bit cloudy. It shows that the calvings in the northern half have continued since.
« Last Edit: August 09, 2016, 05:35:45 PM by Wipneus »

Tealight

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #720 on: August 09, 2016, 11:53:05 PM »
Looks like a big calving in the northern part or the strong northwest winds caused several floating ice islands to turn over. The debris field looks much brighter now. We have to wait for cloud free high-res images to get a better understanding.

Attached is a worldview gif from 4 and 9 August.
« Last Edit: August 10, 2016, 12:06:15 AM by Tealight »

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #721 on: August 10, 2016, 09:08:35 AM »
Not sure about turning over, but the calving did continue there and some icebergs are displaced considerably.
Through the mists or clouds:

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #722 on: August 10, 2016, 07:31:24 PM »
I found two clear Landsat images and see what is going on! The whole iceberg field in front of the glacier has been seriously thinned out. The bergs moved, some a considerable distance, to the south.

Images scaled to 30m/pix for size. You must click to start the animation.

oren

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #723 on: August 10, 2016, 07:47:16 PM »
I have been expecting this since forever. The same happened in August 2014, once the sea ice cleared all hell broke loose. And this year the Atlantic side and the Greenland Sea in particular had very low ice.

TenneyNaumer

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #724 on: August 17, 2016, 05:38:02 AM »
79N and Zachariae are endlessly fascinating.  I remember seeing Ian Joughlin's ice velocity map back in 2007 or so, and when I saw that the northeast ice stream went southwest hundreds of miles and the inclination was pretty steep, it really grabbed my attention. That map is here:  http://static.skepticalscience.com/pics/Figure6.jpg

Do we know if the velocity has increased since 2006 and by how much?

I also have to admit I like the shapes of the calving fronts. 

The other thing is that there used to be an enormous land-fast ice shelf right there that buttressed these glaciers.  I remember it breaking up pretty dramatically in July 2007.  I suppose it probably did that in earlier years, but I was not paying any attention before the winter of 2006-07.  Remember when the sea ice would flow out all down the eastern coast of Greenland? 

johnm33

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #725 on: August 17, 2016, 11:24:18 AM »
"northeast ice stream went southwest hundreds of miles "
I was looking at this just yesterday

nukefix

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #726 on: August 17, 2016, 03:34:18 PM »
S-1A 12.8.2015, preparing to calve more (the crack visible on 8.7 has propagated further)

ps. sorry for the jpeg-artefacts I was a bit aggressive with the settings..


Iceismylife

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #727 on: August 17, 2016, 06:20:36 PM »
http://go.nasa.gov/2bnyU3D

In the floating ice that was once part of Zachariae is that a crack in it or some other kind of artifact?

Tealight

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #728 on: August 18, 2016, 12:03:45 PM »
http://go.nasa.gov/2bnyU3D

In the floating ice that was once part of Zachariae is that a crack in it or some other kind of artifact?

To me it looks like a network of melt pond rivers where two bigger ones form parallel lines.

Click on the image for full resolution
« Last Edit: August 18, 2016, 12:16:37 PM by Tealight »

Shared Humanity

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #729 on: August 18, 2016, 03:28:45 PM »
It is clearly melt ponds and these spell doom for this section of ice that has separated from the glacier. The behavior of this ice shelf will be more like Larsen C in Antarctica. Melt ponds formed across the entire ice shelf, resulting in a catastrophic collapse that occurred in days. I would not be surprised if this entire shelf disintegrated in a single day in the near future, likely not this year as the melt season is coming to a close but soon. Once this area is seasonal sea ice, I think the ice in front of the main glacier will clear out much more quickly each melt season due to surface currents flowing south. This will remove the buttressing effect and speed up the glacier considerably.

nukefix

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #730 on: August 19, 2016, 04:38:19 PM »
S-1A 19.8.2016, the said crack is propagating further. BTW, this image is a downloaded GeoTIFF from PolarView and appears to have 20m resolution (I have some problems interpreting the metadata). Looks great in SNAP!

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #731 on: August 19, 2016, 07:04:36 PM »
The calvings away from the glacier front are in movement, much more than the glacier itself. Here is a detail where an iceberg looses a relative small chip, that topples over.
Note that this chip stays more or less in the same position, while the mother iceberg is thrown back quite a distance. Apparently(!) in violation of Newton's Third Law (the action=-reaction thing).
The two images are aligned to one particular iceberg on the left, all movements are relative to this iceberg.

TenneyNaumer

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #732 on: August 20, 2016, 06:37:52 AM »
Thanks for posting that photo, johnm33 -- perturbing. 

longwalks1

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #733 on: August 21, 2016, 03:38:40 PM »
perurbation     :  a disturbance of motion, course, arrangement, or state of equilibrium; especially :  a disturbance of the regular and usually elliptical course of motion of a celestial body that is produced by some force additional to that which causes its regular motion


Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #734 on: August 21, 2016, 05:40:15 PM »
Some small calvings near the top of the calving front.

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #735 on: August 23, 2016, 12:05:29 AM »
Polarstern provides a good illustration how out of date the Greenland coastline is on Sailwx. It would be nice to see some images from the 79North glaciers calving front. Getting that close to Zachariae would probably be pretty dangerous with those 300m bergs turning.

Tealight

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #736 on: August 23, 2016, 05:55:10 PM »
I believe I found the Polarstern on a Sentinel 2A image. Close to the coordinates reported on Sailwx is a line of broken ice (marked with red arrows). It ends in a polyna where a few pixel are slighly different coloured than typical ice. That should be the ship. Width and length correlate with the ships dimensions

Note: The Polarstern is just 25m wide and 117m long. At native 10m resolution thats slighly less than 2.5*11.7 pixel.
« Last Edit: August 23, 2016, 06:04:20 PM by Tealight »

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #737 on: August 25, 2016, 01:50:23 AM »
http://go.nasa.gov/2bHcQRA

The ice in the channel over from the Zachariae's outlet is taking a beating.  Toggle back through the past few days to see what is what.

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #738 on: August 25, 2016, 11:53:31 AM »
Meanwhile, the fast ice has broken away from the 79N glacier. Some larger calvings have gone too.

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #739 on: August 26, 2016, 11:58:01 PM »
The German research icebreaker R/V Polarstern is working in this area right now, e.g.,

http://www.meereisportal.de/en/seaiceexpedition/where-is-polarstern.html

The focus is on glacier-ocean interactions both from a modern (physical oceanography) and ancient (geology, paleo-oceanography) perspective with groups from Germany, England, and the US all working together. Wish them luck to recover those moored sensors computers placed in shallow waters where ice bergs may wipe them off the bottom of the ocean. A Canadian technician I work with is aboard to help, but I have not heart from him for 2-weeks; even simple text-only e-mails can be hard to get off the ship at times ...
according to the weekly report https://www.awi.de/nc/en/about-us/service/press/press-release/unterwegs-im-norske-trog.html (in English) from the 21st this has been sucessful
Quote
In addition, we were able to recover all of the seven moorings deployed on the mid-shelf in 2014. They had been equipped with sensors in order to measure the circulation of Atlantic water in the trough. In turn, an array of four moorings was subsequently deployed with a similar sensor arrangement, which shall be recovered during a R/V Polarstern expedition next summer. We further resumed the helicopter-based operations for the recovery and redeployment of several geodetic and one seismological station on the mainland of Greenland. Fortunately the weather conditions allowed us to conduct at least two operations per day.
The report is worth reading and says 
Quote
Over the next week we hope to explore along the edge of the 79N ice shelf itself ...... happy days.

we have seen the subsequent track doing exactly that.
Bruce has reported on the bouy thread that data from some deployed buoys can be seen at the Woods Hole site http://www.whoi.edu/page.do?pid=154416

Bruce Steele

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #740 on: August 28, 2016, 11:03:34 PM »
My guess is it depends on how warm the seawater is at the base, if it's warm enough a fairly rapid retreat to the next ridge, and if that happens quickly a slump beyond that.
Take a look at Nioghalvfjerdsfjorden and see what you think will happen when open water extends beyond the trough below it's front.


Bruce Steele

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #741 on: August 28, 2016, 11:26:42 PM »
   http://www.whoi.edu/page.do?pid=154416

So at 500 meters the water temperature is 1.15C Both the bottom of the floating ice tongue and the grounding point of Nioghalufjerdsfjorden are exposed to melt conditions. So too Zacharriae?

TerryM

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #742 on: August 29, 2016, 09:58:19 AM »
According to Dr. Muenchow at


https://icyseas.org/2013/10/31/ocean-circulation-and-melting-glaciers-off-north-east-greenland/


there are no locations between Belgica bank and the mainland that have anywhere near the depths that the new Woods Hole sensors appear to be showing.


Might we be misinterpreting the data somehow?


I think I remember reading that the water in the Belgica Gyre took a number of years to move up the coast. (no link), If this slow spin is present at depth, and if my memory is correct, the warm Atlantic waters being recorded could have entered the gyre back in 2012 or 13.


My own novice thought has been that the speed of the gyre would be dependent on the speed of the southerly flow of Fram, very similar to the way a rapid flow in a river produces a rapid eddy current.
Terry

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #743 on: August 29, 2016, 11:22:55 AM »
repeating what I said in the bouys thread, what is shown in yellow in the  Icy Seas post by Dr Muenchow is the ice surface of the glaciers and the now partly defunct ice shelf off Zachariae.
This means it plots the surface elevation, not the sea floor depth below the ice in those locations. There is a sill (moraine?) in front of the glaciers which leave a much deeper trough behind the sill as they retreat from their (ice age?) maximum extent.
The ITM5 sits on the 79N glacier surface and its probes in the deep water below it.

johnm33

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #744 on: August 29, 2016, 01:18:39 PM »
We're approaching max/min tides meaning an increased exchange of waters, the 'lake' on the north west shore of the shelf is tidal. I think the tidal surges come from the south up the deep channel, but not knowing the times of the daily snapshot makes that's just a guess. http://go.nasa.gov/2c2KM98 this link is from the beggining of the last max/min and it's worth clicking through the following days. I'm thinking we'll see some serious action on both glaciers in the next month, but who knows?

from Terry's link

This is from upthread ht Sidd, I'm assuming the old calving front just n/e of Zacharie is sitting on a morraine and it's looking very vulnerable.
http://www.dmi.dk/fileadmin/user_upload/vandstand_txt_pdf/2016/Danmarkshavn2016.pdf Nearest tide prediction I could find, 740N
Not to be missed http://membrane.com/sidd/greenland-2013/

Bruce Steele

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #745 on: August 29, 2016, 05:00:45 PM »
At the bottom of the itm5 page it says " ITM5 was deployed on a 1.35 m thick ice flow at the mouth of the 79 North Glacier in Greenland on August 23 , 2016 at 41.0 N, 20.9 W during the ARK-XXX/2 (PS1000) cruise on the German Icebreaker Polarstern."
 So I am afraid we have a mystery as to the depth of the sensors in the array. We also I believe have some inconsistancy in the charted depths of the 79N glacial fjord . Johnm33 just posted a 200 meter
contour that shows a 200 meter contour line in the general vicinity of the sensor array but in the earlier posting from John33  dated  April 5 that I  reported below you can see much deeper depths within the fjord.
 Because the array is a d-bar measure and only the pressure /weight of seawater can make the sensors give the readings they are producing and three of them are producing measurements that exceed
200d-bar/ meters I think we can exclude sensor failure. So on the weight of the evidence I believe the depth of the fjord exceeds 500 meters . And because the quote from the ITM5 page says it was deployed on 1.35 meters of ice  that presumably someone had to drill a hole though to place the buoy in the first place I think we should accept the depth as the depth of the water it sits over.
 

Wipneus

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #746 on: September 01, 2016, 07:04:14 PM »
The little bay that was so full of Zachariae calvings earlier this year that some wondered what will happen when it is full has been nearly flushed in days. It too cloudy for S2A images, so back to Sentinel 1.

Espen

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #747 on: September 01, 2016, 08:00:34 PM »
The little bay that was so full of Zachariae calvings earlier this year that some wondered what will happen when it is full has been nearly flushed in days. It too cloudy for S2A images, so back to Sentinel 1.

There is now direct connection to the ocean, and that pulls the debris.
Have a ice day!

Andreas T

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #748 on: September 02, 2016, 10:10:02 PM »
there is a new entry on the Polarsterns blog. https://blogs.helmholtz.de/polarstern/en/2016/09/1527/
It seems they have been very busy to make the most of the opportunity to get into an area which often isn't accessible.

Cate

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Re: Zachariae Isstrøm / Nioghalvfjerdsfjorden / North East Greenland
« Reply #749 on: September 03, 2016, 03:32:04 AM »
That huge floe that's been sitting right out in the road off Zachariae Isstrom---that's got a big crack right running north-south now. Compare Aug 21 and Sept 1.

http://www.arctic.io/explorer/4Xa5A/2016-09-01/9-N79.19674-W16.60698