Author Topic: Ryder Gletscher / Sherard Osborne Fjord / North Greenland (Read 19621 times)

Espen · « **on:** June 01, 2014, 09:56:46 AM »

Ryder Gletscher is situated in Sherard Osborn Fjord between Warming Land / Permin Land and Wulff Land / Aage Bistrup Land.

It seems Ryder is ready for a minor calving soon, the image below show the progress between April 29 2013 and May 31 2014.

Please click on image to enlarge!

Espen · « **Reply #1 on:** August 01, 2014, 03:55:33 PM »

Ryder Gletscher Calving:

As predicted earlier in the season we have a not so often calving at Ryder Gletscher:

Espen · « **Reply #2 on:** August 01, 2014, 04:21:43 PM »

I believe a very similar calving will happen at Petermann this season.

Espen · « **Reply #3 on:** August 02, 2014, 07:02:39 AM »

Landsat showing the calving.

Espen · « **Reply #4 on:** August 02, 2014, 12:42:38 PM »

Here is the animated version: ( a smaller piece took off at the left side of the glacier too)

The calf is about 3,8 km².

Phil. · « **Reply #5 on:** August 02, 2014, 02:54:02 PM »

Looks like the piece behind might go too?

Espen · « **Reply #6 on:** August 02, 2014, 06:23:04 PM »

The interesting thing about the 2 calvings (2006 and 2014) the crack starts from the same point at the right shoreline?

DaddyBFree · « **Reply #7 on:** August 03, 2014, 02:13:44 AM »

That is interesting Espen. Is that a riverbed exiting at the bank there, perhaps dumping warm snowcap melt?

Espen · « **Reply #8 on:** August 03, 2014, 09:05:51 AM »

Yes, there is both a river outlet and a cape, in the close vicinity?

Espen · « **Reply #9 on:** August 03, 2014, 11:19:21 AM »

A little research has shown Ryder is not calving that often, there was a calving in 1999 or earlier similar size as 2006 (there is no images before that), and then again in 2006, and a small one between 2010 and 2013 similar to the one this season (2014). I think the next calving will be delayed because of the recent calving since the back pressure from the cape is now gone.

Espen · « **Reply #10 on:** April 12, 2015, 04:23:14 PM »

Beware this is old news, but I believe it is the first the grand calving of Ryder Gletscher in 2006 is shown in sequences:

I just want to mention that Ryder Gletscher follows the same calving pattern as Petermann Gletscher, it starts with a fissure and develops into a crack, as shown here on an earlier post:

https://forum.arctic-sea-ice.net/index.php/topic,53.msg49939.html#msg49939

andy_t_roo · « **Reply #11 on:** April 13, 2015, 11:58:06 AM »

there must be significant tension in the ice, as the the ice floats away after breaking; the only thing preventing that from happening earlier was the structural integrity of the ice.

does anyone know the the rate of water outflow under the ice? (it must be at least the speed we can see the surface ice moving...)

folke_kelm · « **Reply #12 on:** April 13, 2015, 07:49:43 PM »

Andt_T_Roo

There is never tension on the ice moving ice bergs away from the glacier.
The power to move the calved part away from the glacier is a current of water with low density resulting from bottom melt. The glacier melts from below due to relative warm dense water with high salinity that is flowing into the fjord. Where it comes into contact with the glacier it is melting it and mixing with the fresh glacier melt water, it gets colder but less dense, moving upwards and out of the fjord. This current out of the fjord is moving all icebergs away from the glacier.

The outflow from meltwater from the inland is not known for any glacier as i know, but is is not much compared to bottom melt water. As i know there is some work in progress to get more details and quantification about these mechanisms.

Espen · « **Reply #13 on:** January 17, 2016, 10:04:49 PM »

Ryder Gletscher is preparing for relative large calving again initiated by one of the Caps in Sherard Osborne Fjord.
https://twitter.com/Ecoverycom

Click on image to animate!

Espen · « **Reply #14 on:** July 21, 2016, 11:00:07 AM »

The big story of today, one of the rare occasions when Ryder Gletcher is seen in the calving moment:

Espen · « **Reply #15 on:** July 22, 2016, 11:12:19 PM »

I am proud to present for the first time in internet history and on ASIF in particular a calving "live" at Ryder Gletscher:

Neven · « **Reply #16 on:** July 22, 2016, 11:24:50 PM »

Nice, Espen!

Espen · « **Reply #17 on:** July 22, 2016, 11:47:44 PM »

There is no real explanation for this calving at moment, beside the physical rules that includes the shear point (cape) inside Sherard Osborne Fjord and of course the full moon , but the increased velocity of the glacier may include other facts?

notjonathon · « **Reply #18 on:** July 23, 2016, 02:06:28 AM »

Although psychical rules sound pretty good (the psychical powers of the full moon spread their aura over the ice, perhaps?), I assume you meant "physical rules." Also, might bottom melt cause the front of the glacier to try to float higher, allowing the high tides to give it the extra push needed to fracture the ice?

Tealight · « **Reply #19 on:** July 23, 2016, 03:44:17 PM »

Quote from: Espen on July 22, 2016, 11:47:44 PM

There is no real explanation for this calving at moment, beside the physical rules that includes the shear point (cape) inside Sherard Osborne Fjord and of course the full moon , but the increased velocity of the glacier may include other facts?

There is extensive melt ponding on the glacier with melt water streams flowing down the entire length. The biggest is about 20-30m wide. (2-3 pixel in Sentinel 2) It should have helped the calving event at least a little.

Btw: How did you notice the calving? Its hardly visible on MODIS images.

Iceismylife · « **Reply #20 on:** July 23, 2016, 05:25:28 PM »

Quote from: Tealight on July 23, 2016, 03:44:17 PM

...

Btw: How did you noticed the calving? Its hardly visible on MODIS images.

He has the best eye for calving out there. He probably felt it before he looked. And he is ESL so forgiveness for spelling creativity should be in order.

TerryM · « **Reply #21 on:** July 24, 2016, 01:07:51 AM »

Espen
VERY NICE CATCH !!

notjonathon
Wouldn't the loss of flotation under the tongue cause downward pressure? I believe we saw an instance a few weeks ago, at another glacier, where melt ponds sloshed backwards (up stream) after the weight of a portion of the tongue was suddenly removed by calving.

Terry

notjonathon · « **Reply #22 on:** July 24, 2016, 03:24:46 AM »

Quote

Wouldn't the loss of flotation under the tongue cause downward pressure?

Damn! Now you're forcing me to think. And my last physics class was nearly 60 years ago. But it seems to me that if the floating ice at the front of the glacier were to thin, it would cause upward pressure at the bottom and downward pressure at the top. Go with the old 90% underwater for convenience, and you'd have 90m of ice underwater and 10m above if it were 100m thick; melt it to 80m, and you'd have 72m underwater (pushing upwards) and 8m above water (pulling downwards). Not trying to be exact with my numbers, but as an example. Now what the actual conflicting pressures would do to the ice, I leave to those more learned in the field.

Also, I wasn't really trying to make fun of Espen, for whom I have the highest regard, if not a feeling of awe; but Wiccans, you know.

sidd · « **Reply #23 on:** July 24, 2016, 07:10:48 AM »

" ... might bottom melt cause the front of the glacier to try to float higher ... "

my understanding is that as the bottom melts draft(depth of ice keel) and freeboard (height above sea) decrease by the same fraction. So bottom melt decreases freeboard.

" ... high tides to give it the extra push ..."

this is plausible. bending and fracture are very responsive to thickness, the exponent is large. So a thinner tongue will move more under tidal force and break easier than when thicker.

sidd

notjonathon · « **Reply #24 on:** July 24, 2016, 09:58:45 AM »

sidd--

After Terry so cruelly forced me to think about what I had written, that was the conclusion I came to, also. But since both draft and freeboard are affected, it would logically put more strain on the ice.

Tealight · « **Reply #25 on:** July 24, 2016, 12:42:05 PM »

I seriously doubt the calving has any effect on the melt lakes. The glacier is about 70km long and below sea level for most of its length. NSIDCs BedMachine suggests an elevation of 700m for the melt lakes. This gives a gradiant of 10m per km.

I also measured the size of the calvings. The big block is 24 km² and the smaller is 2.28km². Does anyone know how it compares to big Petermann or Jakobshavn calvings?

Espen · « **Reply #26 on:** July 29, 2016, 10:18:24 AM »

Ryder Gletscher update: Almost at the end of the calving process:

Espen · « **Reply #27 on:** August 01, 2016, 09:33:35 AM »

The 2016 Ryder Calving is complete now:

Shared Humanity · « **Reply #28 on:** August 01, 2016, 03:08:08 PM »

How big is that berg? Not just area but volume as well.

Espen · « **Reply #29 on:** August 01, 2016, 04:01:20 PM »

My current estimate of the main iceberg +/- 30 km² and between 9 and 15 billion m³ (thickness 300 - 500 meter)

RoxTheGeologist · « **Reply #30 on:** August 02, 2016, 08:56:37 PM »

Can you please bring it down to California?

Espen · « **Reply #31 on:** September 07, 2017, 08:54:44 PM »

Ryder Gletscher update:

A suspicious center crack (almost like Petermann) can be observed in this image from Sentinel-2 September 6 2017 (watch inside red circle)

Click on image to enlarge

Tor Bejnar · « **Reply #32 on:** September 14, 2017, 09:04:53 PM »

One lateral crack in the middle of a glacier could be a fluke. Can two be a fluke?
My questions include:

Is the leading edge of the middle part of the glacier flowing faster than the edges?
Is the toe of the glacier getting undercut (or the underside of the middle of the glacier melting faster down-stream of the crack than up-stream of the crack, even if not floating), causing a 'normal' fault in the middle?

Espen · « **Reply #33 on:** August 12, 2019, 07:18:19 PM »

As a surprise to me at least, The Swedish Ice Breaker "Oden" is located in Sherard Osborne Fjord, the same fjord where you will find Ryder Gletscher, and it is the first time I ever observed a surface ship / vessel north of Nares Stræde (Strait):

More info here: https://polar.se/en/about-polar-research/expeditions/ryder-2019/

Tor Bejnar · « **Reply #34 on:** August 12, 2019, 09:43:09 PM »

That's so interesting, Espen.
Revisiting the lateral crevasse, the glacier has advanced about 1.0 km and the crevasse is noticeably wider. (How did Espen even see it 2 years ago!) The end of the glacier has not calved much (about 0.2 km at the 'dip' on the left side), but a little bit everywhere it seems. Sentinel-hub Playground images from 2017 and 2019. The glacier (shelf) has rotated some, with crevasses on the right side opening more. The two images were juxtaposed so the area around the crevasse was made to appear to have moved the least. (Remember, the whole thing flowed north roughly 1 km.

My question remains: why did both this glacier and Petermann get a mid-glacier lateral crevasse.

(a click runs the GIF)

oren · « **Reply #35 on:** August 12, 2019, 10:47:15 PM »

Quote

My question remains: why did both this glacier and Petermann get a mid-glacier lateral crevasse.

Isn't this crevasse created by meltwater flowing on top of the glacier?
I am guessing the middle of the fjord is lower than the sides, and the part nearer the calving front is lower than the part that is farther away, thus a natural "stream" is formed.
I am also guessing that for this to happen there has to be a well-defined fjord, that it doesn't flow too fast, that it has a smooth gradient, and probably some more requirements. Maybe it only happens in ice shelves?

Tor Bejnar · « **Reply #36 on:** August 13, 2019, 06:43:59 PM »

These two transverse ~~lateral~~ crevasses are perpendicular to the mid-glacier stream. For sure a moulin could have formed there, but why the transverse crevasse?

Quote

Transverse crevasses, perpendicular to the flow direction along the centre line of valley glaciers, are caused by extending flow.

[Britannica]
This says to me the leading end of these two ice shelves are moving faster than points upstream of the crevasse. Gravity isn't the obvious culprit as the shelves are floating. Is it tides pulling the center of the shelf?

If so, tides are getting more and more respect around here!

oren · « **Reply #37 on:** August 13, 2019, 07:00:05 PM »

Sorry Tor, I think I missed/misinterpreted the "lateral" in the original post.

Espen · « **Reply #38 on:** August 13, 2019, 08:13:45 PM »

Like at Petermann Gletscher , Ryder Gletscher is forced to calve by their respective surroundings, it basicly works the same way as a (diamond) glass cutter, and this calving below in animation show exactly how the next major calving will happen at Petermann, you find the "glass cutter" at "starboard":

Espen · « **Reply #39 on:** August 28, 2019, 07:12:25 PM »

Made a photo collage out of a Sentinel 2 image and a photo produced by Ulf Hedman onboard the Oden, you can see the 3 small glaciers originating from Permin Land on Ryders Port side (Sentinel 2) and in the background of photo from Oden:

blumenkraft · « **Reply #40 on:** August 28, 2019, 09:05:34 PM »

OMG so cool! Great collage Espen. 👍🏽

I didn't make that connection when i saw the picture on the Oden blog.

News:

Author Topic: Ryder Gletscher / Sherard Osborne Fjord / North Greenland (Read 19621 times)

Shared Humanity

blumenkraft