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b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #100 on: June 13, 2019, 08:32:03 AM »
Amazing animation.
So does the dark color represent wet surface or warmed surface?

I don't know if it's surface temperature or snow wetness or a combination of both.

I did saw the ESS darkening in M8 and M10 band like 2 days before melt ponds became visible in Sentinel.

Also the Greenland darkening Jay posted, corresponds directly to rising temperatures.

I made GIFs showing this in detail. First GIF is yesterdays temperatures on the east coast with time stamps. If you compare the Greenland darkening (in M10 band) GIF 2 (Click to play), it corresponds directly to the rising temperatures.

So i guess the question is, would ice and snow melt that fast or is it temperature we are seeing?

JayW

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Re: The Rammb Slider Thread
« Reply #101 on: June 13, 2019, 11:34:24 AM »

I don't know if it's surface temperature or snow wetness or a combination of both.

I did saw the ESS darkening in M8 and M10 band like 2 days before melt ponds became visible in Sentinel.

Also the Greenland darkening Jay posted, corresponds directly to rising temperatures.


I did a bit of poking around, trying to read stuff well above my pay grade.  This one paper explains a lot I think.  Ultimately, it appears we are likely looking at grain size.  Fresh snow generally falls as dendrites, the pretty, six sided geometric shapes we see portrayed in Christmas movies that's highly reflective.  Over time, the snow metamorphosizes due to factors such as temperature, humidity, compaction, etc.  It turns out that the 1240nm wavelength is sensitive to the grain size (larger grains better absorb this part of the spectrum).  Anyone who has watched a lot of snow melt will have likely noticed that as snow warms to the point of melting, it turns into "corn snow", large grainy snow that loosely resembles ball bearings (at least it reminds me of them). 

I believe that this must be what we are seeing, the metamorphosis from a more flake-like structure, to larger, coarser grains that occurs as a snowpack begins going through thaw-freeze cycles.  So while the sensor is picking up on the increased absorption of the 1240nm wavelength by larger grains, it coincides with the temperature rising above freezing, or any other process that would increase grain size like rain or even compaction.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.the-cryosphere.net/5/831/2011/tc-5-831-2011.pdf&ved=2ahUKEwiRoeeohebiAhXQqFkKHRy6Bw0QFjAMegQIBhAB&usg=AOvVaw39ewk-rkiK8uXp5-YsUAkD
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b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #102 on: June 13, 2019, 11:50:19 AM »
OMG, this makes so much sense. What we see is the structure of the snow.

Thanks so much Jay!

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #103 on: June 13, 2019, 01:03:21 PM »
VIIRS potential for snow retrievals

Several VIIRS bands have good sensitivity to snow structure, especially SWIR bands M8,10,11
Overlaid curves show model snow albedo for various grain sizes

Link >> https://collaboration.cmc.ec.gc.ca/science/rpn/SEM/dossiers/2012/seminaires/2012-11-23/Seminar_2012-11-23_Alexander_Trishchenko.pdf

oren

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Re: The Rammb Slider Thread
« Reply #104 on: June 13, 2019, 02:21:46 PM »
Thanks for the detailed explanation!

JayW

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Re: The Rammb Slider Thread
« Reply #105 on: June 13, 2019, 10:13:17 PM »
VIIRS potential for snow retrievals

Several VIIRS bands have good sensitivity to snow structure, especially SWIR bands M8,10,11
Overlaid curves show model snow albedo for various grain sizes

Link >> https://collaboration.cmc.ec.gc.ca/science/rpn/SEM/dossiers/2012/seminaires/2012-11-23/Seminar_2012-11-23_Alexander_Trishchenko.pdf

Thanks for this awesome find!

An impressively dark, nearly black splotch is emerging in the northern Laptev above 80°N.  Anxiously awaiting the next frames, and how the sensors used for area and extent interpret it.

Still shot, edited to put north up.
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b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #107 on: June 16, 2019, 04:04:11 PM »
@B_lumenkraft: Shit, a can't see anything. Damn clouds.

@JayW: Wow, these clouds, look what's there to see.

I have so much to learn still...

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Re: The Rammb Slider Thread
« Reply #108 on: June 20, 2019, 12:55:46 PM »
The shortwave IR bands M12 and I4 are sensitive to sea surface temperatures.  I had to boost the contrast and "lightness" in ezgif for better detail, I lack the processing skills others her have.  Sorry the shot land masses are a bit distracting.  Lighter is warmer.  Some frames weren't available, so there's a bit of a jump in there.

Bering Strait, needs a click.
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be cause

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Re: The Rammb Slider Thread
« Reply #109 on: June 20, 2019, 12:59:18 PM »
Hi Jay .. this would suit the met thread .. b.c.
Conflict is the root of all evil , for being blind it does not see whom it attacks . Yet it always attacks the Son Of God , and the Son of God is you .

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Re: The Rammb Slider Thread
« Reply #110 on: June 21, 2019, 12:39:42 PM »
The current east of Wrangel Island eating it's way into the pack.
60 hours.
Click to run
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johnm33

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Re: The Rammb Slider Thread
« Reply #112 on: July 04, 2019, 10:33:03 AM »
If anyone cares to do it I would be grateful to see animations of the circular features in the Norwegian sea, which should have been happening the last couple of days. Rammb gives my desktop siezures, and polarview seem to be on holiday.

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #113 on: July 04, 2019, 11:03:53 AM »
Here you go, John. Click to play.

johnm33

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Re: The Rammb Slider Thread
« Reply #114 on: July 04, 2019, 02:56:28 PM »
Thanks b_l, needs to be fully zoomed in on though, perhaps where it's cloudless? john

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #115 on: July 04, 2019, 03:13:58 PM »
Well, for a zoom in, the Norwegian sea is kinda too big to know what area you mean. What circular feature do you mean exactly? That storm on the left?

JayW

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Re: The Rammb Slider Thread
« Reply #116 on: July 04, 2019, 04:30:04 PM »
Glad to see the high resolution I bands updating again.   I don't have the skills, nor the patience and time to create my own RGB composites.  So I emailed feedback to RAMMB about the possibility of plugging in bands to RGB channels.   I didn't get a response,  :( , but if more folks makes that suggestion, maybe they'll add it.   I think it could be useful.   :)
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Re: The Rammb Slider Thread
« Reply #117 on: July 04, 2019, 04:56:00 PM »
create my own RGB composites
If you can provide 3gifs of the same size of exactly the same area with matching timestamps I would be interested to put them together for a test. I'm on metered broadband so I don't play with rammb much.

btw this area east of svalbard looks interesting and quite clear recently. https://go.nasa.gov/325M64G
Worldview with bathymetry inlay
edit: aqua modis is better https://go.nasa.gov/32bUzmK
« Last Edit: July 04, 2019, 05:08:37 PM by uniquorn »

johnm33

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Re: The Rammb Slider Thread
« Reply #118 on: July 04, 2019, 06:58:12 PM »
b_l , Norwegian sea, polarview rebooted and is showing some signs se of 20e 72n but even there I think it's too cloudy/there's too much evaporation.

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #119 on: July 04, 2019, 07:06:41 PM »
Yes, John, i don't see a thing. Sorry. :(

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #120 on: July 04, 2019, 07:08:22 PM »
create my own RGB composites
If you can provide 3gifs of the same size of exactly the same area with matching timestamps I would be interested to put them together for a test.

How would one do that, Jay?

I don't see that setting.

JayW

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Re: The Rammb Slider Thread
« Reply #121 on: July 04, 2019, 08:13:08 PM »
create my own RGB composites
If you can provide 3gifs of the same size of exactly the same area with matching timestamps I would be interested to put them together for a test.

How would one do that, Jay?

I don't see that setting.
It doesn't exist.  I just gave feedback and suggested it, but never got a response, and was trying to recruit others to suggest it.  The overlay feature is nice, but the ability to create RGB composites seems like it could be useful.

I'm busy now, but I'll try to get a few synchronized gifs together soon, to take uniquorn up on the kind offer.
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b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #122 on: July 04, 2019, 08:25:25 PM »
Thanks, Jay, for clarification.


b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #123 on: July 04, 2019, 08:29:24 PM »
If you can provide 3gifs of the same size of exactly the same area with matching timestamps I would be interested to put them together for a test. I'm on metered broadband so I don't play with rammb much.

What do you need? 3 different bands? Which ones?

That could be tricky because often times the times don't match. For example, you get more 'day/night' shots per day than 'geo-colours'.

JayW

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Re: The Rammb Slider Thread
« Reply #124 on: July 04, 2019, 08:57:50 PM »
If you can provide 3gifs of the same size of exactly the same area with matching timestamps I would be interested to put them together for a test. I'm on metered broadband so I don't play with rammb much.

What do you need? 3 different bands? Which ones?

That could be tricky because often times the times don't match. For example, you get more 'day/night' shots per day than 'geo-colours'.
I believe the geo color and natural color are already composites, that's why they take so long to load.

The two combinations I want to try are I2 - M13 - I4. Hoping for a pretty sea surface temp image.
And I1 - M8  - I3 for snow/ice.  My plan was to make a bunch and let uniquorn play with them.
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b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #125 on: July 04, 2019, 09:09:21 PM »
I'm looking forward to them, Jay! :)

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Re: The Rammb Slider Thread
« Reply #126 on: July 04, 2019, 10:17:08 PM »
create my own RGB composites
If you can provide 3gifs of the same size of exactly the same area with matching timestamps I would be interested to put them together for a test. I'm on metered broadband so I don't play with rammb much.

btw this area east of svalbard looks interesting and quite clear recently. https://go.nasa.gov/325M64G
Worldview with bathymetry inlay
edit: aqua modis is better https://go.nasa.gov/32bUzmK

Here are three. Appreciate your efforts!  ;D
I2 then M12  and M13,  I4 was missing too many frames so I had to use M12.  Depending on the output, I'll provide 3 of the Chukchi, as the arts in that area are interesting, and the skies might be clear for a bit.  I'll do some nearer the pole for snow/ice cover later.  All require a click, and I didn't optimize to preserve as much detail as possible.

Added the link just in case I want to revise the same exact view.
http://rammb-slider.cira.colostate.edu/?sat=jpss&z=5&im=24&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=20190704105857&slider=-1&hide_controls=0&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_m13&x=15392&y=13145
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uniquorn

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Re: The Rammb Slider Thread
« Reply #127 on: July 05, 2019, 12:03:08 AM »
Jayw, thanks for looking at the area suggested, maybe best not to clog up this thread with too many images for now. The gifs were turned into a montage(film strip) and contrast adjusted, hopefully sensitively, then combined composed with imagej default rgb settings.
If the result is anything like you expected and you want to continue I'll write a how to in the dev thread. I'll be happy to do one more test. It will take up less space on this thread if you concatenate the three gifs.
Apologies if the result is a bit large at 4MB, similar to the sum of the three parts, also not optimised. rgb=bca abc, I think, in the order you posted, I preferred ice in red rather than green or blue.
edit:decided overnight that contrast adjustment is a bad idea if reanalysis is planned. I've replaced the gif. Also added noaa bathymetry top right (which dithers :( )
« Last Edit: July 05, 2019, 12:02:20 PM by uniquorn »

JayW

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Re: The Rammb Slider Thread
« Reply #128 on: July 05, 2019, 12:36:30 PM »
Jayw, thanks for looking at the area suggested, maybe best not to clog up this thread with too many images for now.

My hope was to see something in the oceans, so the result wasn't what I had hoped.  Maybe just not enough gradient. Or, I wonder if the way I constructed the gifs from screenshots, was not the best decision.  I'll give it another shot later today with a different approach and area of ice/snow using different bands, probably I1 - M8 - M11.
 My instinct is that only three bands that display in greyscale have any chance at working (< 4µm), but maybe I'm wrong.  Here's a list of what's available, unfortunately the "atmospheric correction" band seems useless.

Thanks again for humoring me.
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Re: The Rammb Slider Thread
« Reply #129 on: July 05, 2019, 12:46:43 PM »
Small dispersed floes show a combination of wind and current. That's why I chose that ice edge over shallower bathy area. I don't have a clue about bands, that's A-Team stuff.
The how to is posted here https://forum.arctic-sea-ice.net/index.php/topic,1259.msg211015.html#msg211015
Let's continue there so as not to disrupt this thread. Looking forward to the next test.

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #130 on: July 08, 2019, 06:16:52 PM »
Mesmerizing...

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Re: The Rammb Slider Thread
« Reply #131 on: July 10, 2019, 07:19:57 AM »
What feature is making those waves in the clouds?

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #132 on: July 10, 2019, 08:17:41 AM »
A mountain, Darvince.  :)

This is Svalbard (east part). Clouds going north to south.

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #133 on: July 10, 2019, 01:52:45 PM »
This is M8 band showing the Lincoln Sea at Nares Strait.

This darkening coexistent with the wind pattern on this day.

Doesn't look like ice condition change to me.

Jay, can you comment on what you are seeing here?

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Re: The Rammb Slider Thread
« Reply #134 on: July 11, 2019, 01:42:08 AM »
This is M8 band showing the Lincoln Sea at Nares Strait.

This darkening coexistent with the wind pattern on this day.

Doesn't look like ice condition change to me.

Jay, can you comment on what you are seeing here?

I think it's very low clouds and/or fog hugging the ice, and we are seeing warmer and/or drier winds trying to scour it out. 
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b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #135 on: July 11, 2019, 10:02:10 PM »
I think it's very low clouds and/or fog hugging the ice, and we are seeing warmer and/or drier winds trying to scour it out.

Amazing!

You can even see it in the radar images >> https://forum.arctic-sea-ice.net/index.php/topic,176.msg212564.html#msg212564

Thanks for your answer, Jay.

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #136 on: July 13, 2019, 10:01:48 AM »
This pretty swirl.

Lincoln Sea, M8 band, enhanced contrast.

b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #137 on: July 13, 2019, 10:28:38 AM »
Another one.

Ellesmere on the right, M8 band, enhanced contrast.

JayW

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Re: The Rammb Slider Thread
« Reply #138 on: July 13, 2019, 04:41:43 PM »
Some eddies have formed in the crack of insignificance north of the CAA, and now that the high resolution I bands are updating regularly, we can see them in better detail.  Some flows can also be seen breaking up a bit as well.
Click to play.
« Last Edit: July 13, 2019, 05:07:34 PM by JayW »
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b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #139 on: July 13, 2019, 05:04:20 PM »
... and the thick floes getting ground in the process.

Tor Bejnar

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Re: The Rammb Slider Thread
« Reply #140 on: July 13, 2019, 07:08:15 PM »
  • and the small floes getting ground to nothing
  • and the swirling mixing the shallow water (at least raising salinity a spot at the surface, if not temperature)
  • and the spots of open water with low albedo
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b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #141 on: July 13, 2019, 08:20:16 PM »
Barry!

GeoColor (CIRA) & Band 11: 8.4 µm ("Cloud-Top Phase")

(Click to play)

JayW

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Re: The Rammb Slider Thread
« Reply #142 on: July 13, 2019, 08:56:02 PM »
This shot is centered at roughly 84°N,110°W.  ~18 hours.  Contrast gently enhanced for detail.
A shear line can be seen bisecting the image horizontally.  There's also interesting patches of dark peppered on the left side.  This is band I2.  A general motion towards the Atlantic is also evident.

Click to run
« Last Edit: July 13, 2019, 09:03:20 PM by JayW »
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Tor Bejnar

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Re: The Rammb Slider Thread
« Reply #143 on: July 13, 2019, 09:52:47 PM »
Quote
A shear line can be seen bisecting the image horizontally.
I see two shear lines, actually.  First a shear line in the lower/center part of the GIF, then it stops and a shear line further up (still center) immediately takes over.

I've watched this sort of team-tag movement in Lincoln Sea ice (mostly on the Greenland side of the Sea) many times.
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Re: The Rammb Slider Thread
« Reply #144 on: July 14, 2019, 08:49:23 AM »
Some eddies have formed in the crack of insignificance north of the CAA, and now that the high resolution I bands are updating regularly, we can see them in better detail.  Some flows can also be seen breaking up a bit as well.

That looks amazing to me. There most be very strong currents rising along the coast there? Does any one know what they might be / where they come from?
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b_lumenkraft

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Re: The Rammb Slider Thread
« Reply #145 on: July 14, 2019, 09:26:24 AM »
Does any one know what they might be / where they come from?

I know there are multiple variables at work here. I don't know how to weight them though.

Variables i can think off are momentum due to the pack movement, tides, gyres, upwelling, wind, and of course, currents.

The general direction of the floes is mainly caused by the pack momentum i would say.

Currents become the main driver for floe movement once floes are separated from the pack.

Surface currents are oftentimes rather narrow. They only influence a small part of the pack while winds often times drag on big portions of it.

Also, the Beauford gyre is a variable to consider here. It also puts a drag onto the pack to make it rotate clockwise.

Mercator barely sees current here btw.

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Re: The Rammb Slider Thread
« Reply #146 on: July 14, 2019, 09:55:03 AM »
Does any one know what they might be / where they come from?

I know there are multiple variables at work here. I don't know how to weight them though.
...
Mercator barely sees current here btw.

Yes that's the thing - if there are currents there, they must be new or previously undocumentet.

To my untrained eye the two "twirls" seen in the gif in JayW's post look like mini-cyclones, with considerable vortexicity (if that is a word ...), each having a diameter of appr. 20 km. and a circular movement of perhaps 10 km per day along the perifery.

Very mysterious ...
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Re: The Rammb Slider Thread
« Reply #147 on: July 14, 2019, 11:22:51 AM »
Those twirls, they should be caused by currents, no? But tides may have something to do with this also.

Why is there never an expert on hydrodynamics when you need one??

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Re: The Rammb Slider Thread
« Reply #148 on: July 14, 2019, 11:37:48 AM »
 Appreciate your interest binntho, as b_lumenkraft mentioned there are likely several/many factors at play.  I'm certainly no expert, but the the counter clockwise motion to me suggests there is some upwelling.  I'm basing this on how the atmosphere works, low pressure is associated with rising air. 
  With so little open water, wind stresses seem to be minimal, but perhaps a southerly flow over the land masses of the CAA *could* result in modest coastal upwelling.
  The most mysterious question to me, is whether these exist under the ice, or do they form only due to the opening.  I haven't a clue.  It'll be interesting to see how they behave going forward.
   I think features like this emphasize the value of these sub daily images available from RAMMB, and am grateful that others, especially b_lumenkraft, have also taken an interest.
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johnm33

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Re: The Rammb Slider Thread
« Reply #149 on: July 14, 2019, 12:21:05 PM »
Those twirls, they should be caused by currents, no? But tides may have something to do with this also.

I more or less agree, there's Atlantic water moving along off the shelf at depth, mercator shows this as higher salinity stretching back to Greenland, and there must be tides running in/out of channel so maybe this movement disturbs that deeper water which organises itself into vortices as it flows, an analogy would be electric current>magnetism. Just guessing.
added
Maybe any movement here https://go.nasa.gov/2JGdiyF could shed some light?
« Last Edit: July 14, 2019, 01:43:16 PM by johnm33 »