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A-Team

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Re: The Nares Strait thread
« Reply #700 on: July 11, 2015, 06:09:43 PM »
no animations yet but clicking through these

Thanks to DMI, it is moderately easy to make these, or at least harvest a time series of imagery from the same satellite. Then the issue becomes clouds, tiling coverage and geometric registration.

Below I took the last 16 Sentinel images for Kennedy view and aligned on Hans Island. This resulted in so-so global consistency in alignment, beyond what image-specific rotations could fix. To keep file size down, the images are rotated CW by 36º so that a crop box can cut out extraneous land. The arch is not included; that would be a separate exercise using Kane view.

Tiling two frames for each day is problematic, though a great project for a hypothetical unpaid summer intern.  Sentinel sees through clouds but the downside is different geometry for each orbit.

Click to view animation ... it did not work out reducing width to 700 pixels. The pause is on July 10th. I'll post a Petermann Glacier cut-out over at that forum.
« Last Edit: July 11, 2015, 06:38:01 PM by A-Team »

ghoti

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Re: The Nares Strait thread
« Reply #701 on: July 12, 2015, 07:30:10 PM »
Looks like the base of the "flying buttress" blew out today (July 12). Looks like we'll soon be trying to track chunks of ice flowing out the Nares.

oren

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Re: The Nares Strait thread
« Reply #702 on: July 13, 2015, 12:10:26 AM »
I put together a crude animation of Kane basin, using daily AQUA images from DMI. It starts from June 20th and goes on until July 12th, with many gaps in between where images had too many clouds.
I think it shows nicely the crumbling of the arch, which was visibly cracked away and started moving on July 9th (the frame with the little extra pause).
To my layman's eye it seems the crumbling happened under pressure from the crushed ice coming from the northeast, and after losing some of the buttressing of the fast ice to the west.

Edit: managed to make it animate at last, see new post below.
« Last Edit: July 13, 2015, 06:43:41 PM by oren »

Laurent

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Re: The Nares Strait thread
« Reply #703 on: July 13, 2015, 11:12:48 AM »
This is not a GIF ? but an image "png".
Follow that video, it should help :

Tor Bejnar

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Re: The Nares Strait thread
« Reply #704 on: July 13, 2015, 02:45:15 PM »
Ice bridge is breaking up nicely, finally! (at least at the edges)  :D
From yesterday's MODIS:
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Neven

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Re: The Nares Strait thread
« Reply #705 on: July 13, 2015, 04:07:33 PM »
Yup, there she blows. Thanks, Tor.
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oren

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Re: The Nares Strait thread
« Reply #706 on: July 13, 2015, 06:41:34 PM »
I put together a crude animation of Kane basin, using daily AQUA images from DMI. It starts from June 20th and goes on until July 12th, with many gaps in between where images had too many clouds.
I think it shows nicely the crumbling of the arch, which was visibly cracked away and started moving on July 9th (the frame with the little extra pause).

Click to animate  8)

Tor Bejnar

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Re: The Nares Strait thread
« Reply #707 on: July 13, 2015, 08:15:25 PM »
Attached a 40m/pix detail of Sonia's floe or iceberg located in the main stream just outside the Petermann fjord (direction top of this image), data from 2015-01-21. As can be seen the white is part of a bigger and darker floe. ...
(It was later determined to be a floe, not a berg - lack of a long shadow.)

It got caught by the Kane Basin ice bridge.  Can we find it?
(Wipneus' image from January 21, 2015)
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Andreas T

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Re: The Nares Strait thread
« Reply #708 on: July 13, 2015, 08:30:46 PM »
Thanks for the animation, Oren, it shows nicely how the ice north of the arch is broken up before the arch starts to give way. It is moving back and forth, but what is driving that movement? I seem to remember Andreas Muenchow writing that tides are quite weak there.

Neven

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Re: The Nares Strait thread
« Reply #709 on: July 13, 2015, 09:59:12 PM »
Yeah, thanks a lot for the animation, oren. I've adjusted it a bit and used it for a blog post on the ASIB.
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oren

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Re: The Nares Strait thread
« Reply #710 on: July 13, 2015, 10:53:17 PM »
Yeah, thanks a lot for the animation, oren. I've adjusted it a bit and used it for a blog post on the ASIB.

Cool!

johnm33

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Re: The Nares Strait thread
« Reply #711 on: July 13, 2015, 11:40:14 PM »
Thanks for the animation, Oren, it shows nicely how the ice north of the arch is broken up before the arch starts to give way. It is moving back and forth, but what is driving that movement? I seem to remember Andreas Muenchow writing that tides are quite weak there.
The tidal range is limited but the tidal race through the narrows is quite fast and the southern flow holds fast to the western/north shore, and is as turbulent as the flow down the east coast of Greenland.

Tor Bejnar

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Re: The Nares Strait thread
« Reply #712 on: July 14, 2015, 09:36:59 PM »
Where is Sonia's ice floe hiding?
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Tor Bejnar

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Re: The Nares Strait thread
« Reply #713 on: July 15, 2015, 04:55:21 AM »
I wonder how big a floe will get through Smith Sound.  The largest piece of the old ice bridge could thread its way through or it could get broken into pieces.
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johnm33

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Re: The Nares Strait thread
« Reply #714 on: July 15, 2015, 10:58:54 AM »
Latest Terra from DMI


johnm33

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Re: The Nares Strait thread
« Reply #715 on: July 15, 2015, 03:43:57 PM »
Clicking between the two images gives a little insight into tide/wind interplay 13th.
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150713AQUA.jpg
14th. http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150714AQUA.jpg


johnm33

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Re: The Nares Strait thread
« Reply #717 on: July 18, 2015, 11:32:26 AM »
The winds have shifted, they're now blowing south at about 20kph, the southern end is clouded but this image shows clear signs of the ice moving south again compared to the last of the previous list.

and if you want to click between them- http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150717TERR.jpg

Andreas Muenchow

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Re: The Nares Strait thread
« Reply #718 on: July 18, 2015, 03:28:16 PM »
Yes, the winds are now from north to south now, but Hans Island

http://dalriada.sams.ac.uk/aws_hans/

shows only weak winds at about 2 m/s which comes to 7.2 km/h. This morning's 08:40 MODIS Aqua image

http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2015199084000-2015199084500.250m.jpg

shows the ice moving from the Greenland coast towards the Ellesmere Island coast in Robeson and Kennedy Channel. Winds cause surface ocean or ice flow at angle to the right of the wind (Coriolis force does this in balance of forces between surface friction and Coriolis). So, let the flushing begin, finally ;-)
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johnm33

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Re: The Nares Strait thread
« Reply #719 on: July 18, 2015, 09:38:15 PM »
My bad, I was looking at the southern end of Kane for wind speed

Andreas Muenchow

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Re: The Nares Strait thread
« Reply #720 on: July 19, 2015, 01:41:00 AM »
@Johnm33:

Nothing wrong with that location; I would have picked it as the most relevant for the flushing of ice out of Nares Strait, too, but how far off the ground are those model winds? Furthermore, how well does the model agree with direct wind observations such as those on Hans Island?
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johnm33

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Re: The Nares Strait thread
« Reply #721 on: July 19, 2015, 11:48:36 AM »
This is yesterday at 15:00 close to Hans Island, the wind speed is about double down at southern Kane, same pattern today just slower, so good for flushing.

Espen

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Re: The Nares Strait thread
« Reply #722 on: July 19, 2015, 07:45:44 PM »
The break up of Nares Strait and Petermann Fjord in progress, but somehow later than I expected, we got to be prepared for Andreas arrival ;):
« Last Edit: July 19, 2015, 07:52:59 PM by Espen »
Have a ice day!

A-Team

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Re: The Nares Strait thread
« Reply #723 on: July 19, 2015, 08:18:22 PM »
Awesome what a difference a day can make ... look how much Petermann opened up in 24 hrs. Let's keep an eye out for calving too, what with buttressing back pressure being so rapidly reduced.

I looked with a high resolution Sentinel pair for where the next break might be ... some possibilities, nothing definitie. Not change yet in the ice sheet's calving front.
« Last Edit: July 19, 2015, 09:10:10 PM by A-Team »

Andreas T

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Re: The Nares Strait thread
« Reply #724 on: July 19, 2015, 08:29:07 PM »
I am looking forward to images from Oden as it goes up Nares strait. The ice north of it looks like it is ready to be flushed towards it. No large floes which might get stuck.

johnm33

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Re: The Nares Strait thread
« Reply #725 on: July 20, 2015, 01:54:21 PM »
Beneath the clouds the southern end is breaking out, if the winds persist for a few days, and at present they're still blowing to the south [6kph] at the exit to Kane basin, we could see the whole strait flowing.
On the 16th the wind was still holding back the ice
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150716s01a.ASAR.jpg
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150717s01a.ASAR.jpg
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150718s01a.ASAR.jpg
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150719s01a.ASAR.jpg
and the top end is just smashed

Espen

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Re: The Nares Strait thread
« Reply #726 on: July 22, 2015, 08:55:50 PM »
There is a crack in the Nares plug:
Have a ice day!

Andreas Muenchow

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Re: The Nares Strait thread
« Reply #727 on: July 22, 2015, 11:06:58 PM »
More than one by now. Also check out the massive upwelling along the Arctic coast of the Canadian Archipelago indicative of strong winds from east to west that move the apparently very loose Arctic sea ice offshore or to the north.

Hans Island winds have been 15 knots (7-8 m/s) for the last 48 hours.

There is also a massive sediment plume coming from a river that traces back to the land-termianting Hidatha (spelling?) Glacier. The river discharges into southern Kane Basin. Hope to write this all up more tidily in my next blog post. Greenland side of Kennedy Channel largely free of ice as the wind causes "upwelling" there (and downwelling off Ellesmere). Ocean dynamics beautifully visualized by the ice as a tracer for surface ocean flow.
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oren

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Re: The Nares Strait thread
« Reply #728 on: July 22, 2015, 11:09:10 PM »
More than one by now. Also check out the massive upwelling along the Arctic coast of the Canadian Archipelago indicative of strong winds from east to west that move the apparently very loose Arctic sea ice offshore or to the north.

Hans Island winds have been 15 knots (7-8 m/s) for the last 48 hours.

There is also a massive sediment plume coming from a river that traces back to the land-termianting Hidatha (spelling?) Glacier. The river discharges into southern Kane Basin. Hope to write this all up more tidily in my next blog post. Greenland side of Kennedy Channel largely free of ice as the wind causes "upwelling" there (and downwelling off Ellesmere). Ocean dynamics beautifully visualized by the ice as a tracer for surface ocean flow.

Andreas - when you do, please post a link to your blog, I'll be very interested in reading it.

Andreas T

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Re: The Nares Strait thread
« Reply #729 on: July 25, 2015, 11:30:37 AM »
I too enjoy reading Andreas M's blog posts, he is a very busy man at the moment so I am taking the liberty of posting a link although I am an entirely different Andreas
http://icyseas.org/ you can also find the link quickly in Andreas Muenchows profile or on Neven's blog page.

JER

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Re: The Nares Strait thread
« Reply #730 on: July 26, 2015, 12:17:22 AM »
Would anyone please like to take a guess regarding whether it is going to be feasible to travel this route and hopefully get ashore in various places, especially on Baffin and Ellesmere Islands and on Greenland well north of Qaanaaq? http://www.lifeonthinice.org/data/web/20150818_20150906_Itinerary.jpg

Departing Kangerlussuaq on August 18; traveling the route clockwise; returning to Kangerlussuaq September 6. The vessel is ice-reinforced, but not an ice-breaker.

Cheers,
Jenny
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JER

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Re: The Nares Strait thread
« Reply #731 on: July 26, 2015, 12:35:03 AM »
Just to be clear, I'm concerned about the coastal regions that are still showing 50-100% ice concentration on the Uni Bremen site.
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Re: The Nares Strait thread
« Reply #732 on: July 26, 2015, 02:38:37 AM »
Would anyone please like to take a guess regarding whether it is going to be feasible to travel this route and hopefully get ashore in various places, especially on Baffin and Ellesmere Islands and on Greenland well north of Qaanaaq?

Hi Jenny,

Andreas Muenchow (see just above) is in the area in Oden as we speak. Rather than guess, instead hope that he has time to check in here and answer that question! Here's the hashtag, in case that helps:

https://twitter.com/hashtag/Petermann2015

Personally I don't see the ice in Baffin Bay lasting that much longer, but then I've never been further north than Oslo!


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JER

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Re: The Nares Strait thread
« Reply #733 on: July 26, 2015, 03:33:31 AM »
Thanks, Jim.

I'm also guessing (hoping!) that there will be enough melt along the coast of Baffin Island to get ashore there in some locations. But I'm particularly concerned about the heavy ice hanging on in Kane Basin and in all the bays along the southeast coast of Ellesmere.

Hopefully news from Oden will clarify the situation.
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Andreas Muenchow

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Re: The Nares Strait thread
« Reply #734 on: July 26, 2015, 03:46:22 AM »
Jer:

You should be fine if you stay on the Greenland side up to Qaanaaq and Smith Sound. It should also be possible to cross over the the Canadian side from there, perhaps visit Grise Fjord, then head south again. I very strongly recommend against going any farther north. The moment you cross Smith Sound and Cape Sabine, there is no way to assure you or your ship will get back out. Many larger ships got crushed, stranded, or blocked at the endtrance to Kane Basin for the last 150 years. Even if it looks good for a day or two because the winds are favorable, the very strong tides, the fickly winds, and the ice shifting fast, this is not something to take lightly, it is not a place to go without lots of resources.

The Arctic is not a place to count on luck. be careful, enjoy your freedom of movement, enjoy your boat gives you. Just don't sink it all by trying to do too much without proper preparation that may take years.
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Andreas Muenchow

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Re: The Nares Strait thread
« Reply #735 on: July 26, 2015, 03:50:40 AM »
Just to be clear, I'm concerned about the coastal regions that are still showing 50-100% ice concentration on the Uni Bremen site.
While this is a very good site, it is not a good product to navigate by. The resolution is too coarse and not always accurately represing actual ice conditions. You should be looking at LandSat (free) or RadarSat (very expensive) at 30 m resolution to get a feel for what the ice may look like from the ground. There are many resources here on these forums (Sentinel), but Uni Bremen ice maps are NOT a tool to plan an actual sail with, because the pixels are too big.

Edit: I am not on Oden until next wednesday or so. Even this powerful icebreaker will have a very hard time navigate through Kane Basin. It almost appears that more ice enters from the north than exits in in the South,
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JER

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Re: The Nares Strait thread
« Reply #736 on: July 26, 2015, 03:58:27 AM »
Thanks very much, Andreas -- greatly appreciated!

I'm not responsible for doing the actual planning or navigating; thankfully, there are people far more knowledgeable than I am who are in charge. (I'll be doing photography.) I'm trying to anticipate where we'll likely be able to go and which locations won't be reachable.

Do you think it might be feasible to get farther north than Grise Fjord by late August?

All the best,
Jenny
@LifeOnThinIce

EDIT: "farther north than Grise Fjord" along the coast of Ellesmere.
« Last Edit: July 26, 2015, 04:07:31 AM by JER »
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A-Team

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Re: The Nares Strait thread
« Reply #737 on: July 26, 2015, 05:47:04 AM »
This is a particularly problematic year. The ice has backed in again to Petermann fjord, refilling it. Melt lakes on the ice shelf peaked about 3 weeks ago, little is left for steam drilling; and the 35 km of kayakable central drainage never filled.

I would use Sentinel here for ice. It's free and has almost daily coverage at this latitude, see below. There's preview coast-hugging footage at DMI http://ocean.dmi.dk/arctic/morrisjessup.uk.php and high resolution full Baffin coverage at ESA https://scihub.esa.int/dhus/

A leg of the Amundsen just got cancelled, GeoTraces sciences. As I read it, 2-3 commercial supply ships wanted an icebreaker to fulfill fuel contracts with small coastal communities, a non-emergency situation but one that was costing them money to stand off waiting for the ice to clear. They got the government to issue the necessary orders. Nothing else was available as icebreaker because of budget cuts.

Instead of carrying 40 scientists deep into the Arctic to research climate change, the Amundsen has been temporarily reassigned to break ice for several commercial supply ships.

The Amundsen on Sunday pulled in its scientific probes, did a U-turn in Davis Strait – between Greenland and Nunavut – and headed to the south tip of Baffin Island.

“The Amundsen has never been diverted from science for ice breaking duty in the Arctic according to the Captain,” wrote Dr. Cullen, a University of Victoria researcher whose Geotraces project relates to the impacts of ocean acidification and climate change effects.

He said research projects, some of which took four years to plan, will have to be cancelled. Dr. Cullen said he understood the urgency of helping supply ships, but was disappointed the Coast Guard didn’t have any other vessels available.

Johnny Leclair, the Coast Guard’s acting assistant commissioner for the Central and Arctic Region, said the Amundsen had to be reassigned because of “harsh conditions.”

He said two other Coast Guard vessels in the region weren’t available. The Pierre Radisson is busy helping a fuel tanker trapped in ice in Frobisher Bay and the Terry Fox had to be sent back to port in Newfoundland to resupply after escorting ships through the ice.
http://www.theglobeandmail.com/news/british-columbia/arctic-research-expedition-put-on-hold-after-vessel-diverted-to-break-ice/article25618672/
« Last Edit: July 26, 2015, 06:00:59 AM by A-Team »

JER

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Re: The Nares Strait thread
« Reply #738 on: July 26, 2015, 08:54:35 AM »
Thanks a lot, A-Team -- very helpful!

I heard about the Amundsen a couple days ago. Terrible situation for the scientists.
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Neven

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Re: The Nares Strait thread
« Reply #739 on: July 26, 2015, 12:03:25 PM »
Jenny, if after your journey you want to use the Arctic Sea Ice blog to share images or texts, send me a mail.
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Re: The Nares Strait thread
« Reply #740 on: July 27, 2015, 12:13:33 AM »
Great, Neven. Thanks!
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Andreas T

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Re: The Nares Strait thread
« Reply #741 on: July 31, 2015, 09:59:39 PM »
according to http://www.sailwx.info/shiptrack/shipposition.phtml?call=SMLQ
the Oden should be getting near the ice by now.

ghoti

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Re: The Nares Strait thread
« Reply #742 on: July 31, 2015, 10:12:39 PM »
According to http://oden.geo.su.se/map/ their speed has dropped to near 0. They must be in the ice now.

A-Team

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Re: The Nares Strait thread
« Reply #743 on: August 01, 2015, 05:56:35 AM »
speed has dropped to near 0. They must be in the ice now.
Been doing some probing it look like, then backing out and trying somewhere else. Or they may be doing planned science experiments. Red lines are the nominal course in and out. It clears up quite a bit the way they are headed and Petermann is fully accessible.

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Re: The Nares Strait thread
« Reply #744 on: August 01, 2015, 07:56:44 PM »
How does one differentiate between cloud-cover and ice on Sentinel images (other than by experience)?
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Tor Bejnar

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Re: The Nares Strait thread
« Reply #745 on: August 01, 2015, 11:27:57 PM »
Jenny,
Basically, Sentinel sees through clouds.  There are some effects, sometimes, mostly away from the center, and you can get what appear to be shadows or brightening.  I think all the 'white' on the lower left of the above image is bits of ice.  Attached is an enlargement of some of that area.  I wonder if the white 'worm' path on the right side (centered top-to-bottom) is the ship passage.
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Re: The Nares Strait thread
« Reply #746 on: August 02, 2015, 01:30:00 AM »
Thanks, Tor. Why is some of the ice whitish/light grey, while some is dark grey/nearly black? Different ice densities or surface characteristics?

"I wonder if the white 'worm' path on the right side (centered top-to-bottom) is the ship passage."

Interesting. Seems to be roughly in the right place.
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Re: The Nares Strait thread
« Reply #747 on: August 02, 2015, 12:47:36 PM »
Why is some of the ice whitish/light grey, while some is dark grey/nearly black? Different ice densities or surface characteristics
I am a learner in that respect myself but what I know so far is that these radar images are basically showing gradients in terrain, you see one side of a mountain as a bright area, the other as a dark area. Which side is bright and which dark depends on orientation of the satellite, the attached images were taken in different orientation. It looks like the mountains are illuminated from the side but of course the "illumination" is produced by the satellite radar.
It doesn't just show largescale sloping gradients it also shows roughness. It picks out crevassing on glaciers and cities in light shades because there are different echoes from the top and bottom of buildings for example close together.
On smaller scales broken up bits of ice also shows up brighter than flat expanses of ice. But old multiyear ice also has a bumpier surface than smoother one year ice. Then there is the question of what surface does the radar "see". The frequencies which it uses are AFAIK reflected differently by snow and ice and water. I think this is what gives those bands on the ice cap seen in the bottom left of the images. Thick snow and firn seems to always appear bright.
An important difference between the 3107 and 0108 images is that the water surface (identifiable from the visible terra image) is also bright in some places in the 3107 image. Rough water surface, waves also give a "bright" response, depending on the orientation of the satellite.
Despite the different times these images were taken there are recogniseable ice floes in all three. How different they can appear shows how much background information is needed to interpret these reliably. Sometimes it is easy to make an educated guess, sometimes not so much. Best I can do at the moment is look carefully at many images and detect patterns.
A good place for compareable visible and radar images is
 http://ocean.dmi.dk/arctic/kane.uk.php
sorry I haven't taken the time to size and crop the images to match, I guess as a photographer you'll see that anyway, Jenny
« Last Edit: August 02, 2015, 01:05:41 PM by Andreas T »

JER

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Re: The Nares Strait thread
« Reply #748 on: August 02, 2015, 11:59:53 PM »
Thanks, Andreas T. Very interesting and helpful.
As a result of climate change, "The Arctic is the ecological equivalent of a war zone." -- Jenny E. Ross

ghoti

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Re: The Nares Strait thread
« Reply #749 on: August 21, 2015, 08:09:57 PM »
I've always wondered about the thickness of the ice in the Lincoln Sea given the various modeled sources of thickness maps. Now the Oden is in the Nares and is seeing chunks of ice flowing in from the north. They posted a photo.

https://twitter.com/SjoV_isbrytning/status/634730153927680000

The estimate from the tweeter is that the pieces of ice they are seeing are 4-5m thick flowing in from the north.