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Messages - nukefix

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The GRACE satellite was an amazing tool from April 2002 until June 2017 & I look forward to seeing even better results from GRACE-FO:
Unfortunately there are serious problems on-board GRACE-FO, so the data-quality is likely to be a lot worse than for the original GRACE  :(

my take is that it then took three years for sufficient seawater ingress to float the basal ice in the first trough and have that break through the overburden of glacial discharge.
The glacier is too thick to float and both GPR & seismic indicate it's solid ice until water-permeated glacial till at the bottom. The meltwater is fresh and it's being dumped into the fjord continuously. Can you find a scientific publication where the authors argue that the saltwater gets to penetrate upstream?

According to this paper:

...the salinity of the Subglacial discharge, Submarine meltwater and Basal Submarine meltwater is zero, which would not be possible if saline waters were penetrating into and under the ice-stream. Case closed?

So I'm guessing the build up of ice at the calving front is just a logjam of bergs waiting to be melted/lifted above the cill hence the pulsed release of bergs associated with tidal extremes.
AFAIK the grounding line of Jakobshavn is at the calving front, or very close to it. That would mean that the fjord waters are not penetrating under it. If they did, the tidal signal would be detectable far upstream from the calving front, and I don't think that is the case.

The following paper states:
We hypothesize that Jakobshavn Isbræ maintains a short floating tongue from winter to early summer, when ice flow exceeds ice loss by calving and the glacier front advances. In summer, iceberg calving surpasses ice flow, and the glacier front retreats, becoming nearly grounded by late summer.

There's also a feature midstream at the bottom of the image which is what I imagine a giant berg would look like moving in the stream.
The channel is full of ice upstream from from the grounding-line, so certainly in that position. Thick ice acts like a viscous fluid (like honey).

Nice example of iceberg collapse at the mouth of the Ilulissat icefjord. 3MB animated GIF attached.

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