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Author Topic: Siberian Arctic coast  (Read 36151 times)

Shared Humanity

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Re: Siberian Arctic coast
« Reply #100 on: May 27, 2017, 12:15:52 AM »
I cannot imagine how FYI could ridge to 10m thick ice. Could this be some of the last thick ice that huddled near the CAA that broke away several years ago and made a lonely journey to the ESS?

Hyperion

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Re: Siberian Arctic coast
« Reply #101 on: May 27, 2017, 12:32:35 AM »
Seriously. This is what the coastline, and the seafloor looks like all around that area. If its "less than ten metres deep then there is bound to be all sorts of pingos, domes caused by dissociating clathrates, rubble from eruption of said domes and the keels of old thick bergs traveling through.
 
But of course there very might well be 10m deep chunks of old multiyear ice embedded in that floe too. Or the keels of pressure ridges from its multiple crush and assemble process this winter too.
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Andreas T

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Re: Siberian Arctic coast
« Reply #102 on: May 28, 2017, 05:42:21 PM »
looking through previous years these strandings are quite common and occur at this spot and a few others. Similar to a shoal along the Alaskan coast I can't remember the name of. On closer inspection I can see another two strandings in that same frame I posted above.
Later in the year sediment stirred up by waves (?) is clearly seen in that shallow area. At the moment it seems to be coming from further east.
Last year the crew of Northabout posted an image from the Laptev sea http://polarocean.co.uk/stamukha/
of  a "stamukha" which seems to be what I expect is grounded there. Ridging can, from pictures I have seen, tilt floes sideways, so making a 10m ridge out of less than 2m ice would seem quite possible. Multiyear ice does not get that thick without ridging either because thick ice slows further freezing (reduced heat transport to cold surface)

Andreas T

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Re: Siberian Arctic coast
« Reply #103 on: June 07, 2017, 08:24:33 AM »
outflow from rivers is starting to melt sea ice at their mouths. The ice in Chaunskaya bay is becoming less blue, this is due to surface water leaking away, the ice becoming more porous.

Andreas T

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Re: Siberian Arctic coast
« Reply #104 on: June 08, 2017, 11:44:07 PM »
In the west the bay of Ob is changing very rapidly. disappearing snowcover, surface water appears and disappears within just a few days.

Pmt111500

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Re: Siberian Arctic coast
« Reply #105 on: June 09, 2017, 05:27:03 AM »
I cannot imagine how FYI could ridge to 10m thick ice. Could this be some of the last thick ice that huddled near the CAA that broke away several years ago and made a lonely journey to the ESS?
SH, this happens on occasion even in northern Baltic Sea, the trick to get a 10m thick wall of ridged ice is actually not as hard as most tend to think. You only need to wedge a somewhat thick floe, say 70cm, of say 20m in diameter, between two larger pieces of ice, at an angle. This then acts as an anchor point to the rest of the ice.
The trick is most of the wedged ice is still under water so the force making the initial ridge has not to be so strong as many would think. A strong winter storm exerting pressure on a vast field of ice behind the wedging floe can pretty easily push even a such a small floe at an angle. I've seen 10 m floes at 45 degrees over in the sea. A protrusion of 2 meters above smooth ice in pictures could have over 8 meters of ice in the ocean. No doubt some of the wedged ice can snap off the initial wedged floe so the ice-breaker captain must use his experience to estimate the true thickness of these ridges. Hope this helps.

I might add that the fact that there are few if any time-lapse videos of this process is likely due the fact that most people want to stay very closely inside in such weather and not risk losing their equipment. Likely over 15m/s winds + windblown snowcrystals would likely clog the view from a camera anyway if it's anchored strongly enough. Some o-buoy type of rig in a correct location could probably do it.
« Last Edit: June 09, 2017, 05:50:47 AM by Pmt111500 »
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Pmt111500

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Re: Siberian Arctic coast
« Reply #106 on: June 09, 2017, 07:29:48 AM »
made a cartoon of sorts about this, it's of course no good practice to anthropomorphize ice floes, but, as the idea came this is the result. Afaik, ridges nearer to the shore are on average higher than those out on the open seas.
« Last Edit: June 09, 2017, 07:50:04 AM by Pmt111500 »
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johnm33

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Re: Siberian Arctic coast
« Reply #107 on: June 09, 2017, 07:15:27 PM »
Would those broken floes not tip sideways at some point, and if they're 10m thick that gives us one dimension of the necessary geometry, one end gets saturated and over they go?

Jim Hunt

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Re: Siberian Arctic coast
« Reply #108 on: June 09, 2017, 10:19:19 PM »
As luck would have it O-Buoy 14 stumbled across some upended ice last summer, albeit nowhere near Siberia:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2016-images/#OBuoy14

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Cid_Yama

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Re: Siberian Arctic coast
« Reply #109 on: June 10, 2017, 12:24:56 AM »
If I were there I would be careful where I stepped.  What an awesome picture.


Andreas T

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Re: Siberian Arctic coast
« Reply #110 on: June 10, 2017, 10:04:43 PM »
some other images I collected of pressure ridges from various sources

dingojoe

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Re: Siberian Arctic coast
« Reply #111 on: June 28, 2017, 05:42:12 PM »
outflow from rivers is starting to melt sea ice at their mouths. The ice in Chaunskaya bay is becoming less blue, this is due to surface water leaking away, the ice becoming more porous.

Intermittent cloud cover makes it hard to get a nice clean shot of the whole East Siberian Sea, but almost all the fast ice has broken up, and what's left should break up in the next few days.  What's most interesting to me is the gap of open water between the fast ice and the main ice pack.  It would seem conducive to a rapid melt out of the formerly fast ice.  We'll know soon.