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Author Topic: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland  (Read 701571 times)

nukefix

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2000 on: January 11, 2019, 03:02:19 PM »
Glacier-ice is malleable at depths of 30m and deeper. Therefore the ice-stream channel must be full of ice until the grounding-line (which for Jakobshavn is estimated to reside within ~1km of the calving front depending on the season) even if the depth of the channel varies. That being said, meltwater channels do form under the ice-stream.

Quote
Surface meltwater-induced velocity variation is a quasi-diurnal signal. Podrasky et al. (2012) detected an amplitude of up to 0.1 m d−1 diurnal signal 20–50 km upstream from the terminus of Jakobshavn Isbræ

https://search.proquest.com/openview/2b991b9bb1ea4dbf97777598550b275e/1?pq-origsite=gscholar&cbl=105732

Espen

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2001 on: January 12, 2019, 02:04:41 AM »
Glacier-ice is malleable at depths of 30m and deeper. Therefore the ice-stream channel must be full of ice until the grounding-line (which for Jakobshavn is estimated to reside within ~1km of the calving front depending on the season) even if the depth of the channel varies. That being said, meltwater channels do form under the ice-stream.

Quote
Surface meltwater-induced velocity variation is a quasi-diurnal signal. Podrasky et al. (2012) detected an amplitude of up to 0.1 m d−1 diurnal signal 20–50 km upstream from the terminus of Jakobshavn Isbræ

https://search.proquest.com/openview/2b991b9bb1ea4dbf97777598550b275e/1?pq-origsite=gscholar&cbl=105732

From what I read it doesnt explain why we have tabular icebergs showing up again?
Have a ice day!

johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2002 on: January 13, 2019, 12:28:13 AM »
The grounding line in that paper is what I think of as the strand line, where the wall of ice moving down the fjord actually touches down on bedrock, beyond there upstream I'm thinking it's supported by bouyant dense ice, a melange if you will that fills the chasm. The tabular bergs slide/grind on that melange and are floated west by tidal movement.

johnm33

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johnm33

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Re: Jakobshavn Isbræ / Ilulissat Isfjord / West Greenland
« Reply #2004 on: January 15, 2019, 10:53:50 PM »
Some calving taking place, looking at 12:00 the north stream has pushed into the bay, and to the right there's some outflow from area north of what will become the island, the main glacier releases some more tabular bergs some of which have turned.

from Polarveiw
 Grounding line/Strand line, if the glacier is grounded then some real retreat is possible, if it's current calving front is a strand line then the fluidity of the base upstream will inhibit retreat and advance will only be possible if the bergs at the face are small enough to float pass the shallow strand line. I don't think that's likely soon but when it happens it could be quite spectacular, probably needs a clear fjord for the best show. I guess.