Support the Arctic Sea Ice Forum and Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - JayW

Pages: [1] 2 3 ... 9
1
Arctic sea ice / Re: The 2019 melting season
« on: Today at 11:47:15 AM »
As mentioned in the RAMMB slider thread, under clear skies, the shortwave IR bands I4, M12, and M13 are sensitive to surface temperatures and have the ability to detect sea surface temperatures.

Attached is a 32 hour loop (June 23, 16Z to 25, 4Z)  of the Laptev, with discharge from the Lena river seen spreading from the lower left corner.

Band I4 with band M13 50% overlay, this helps hide the clouds somewhat.  Contrast  enhanced and lightened for detail.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=5&im=48&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&opacity%5B1%5D=0.5&hidden%5B0%5D=0&hidden%5B1%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_i04&p%5B1%5D=band_m13&x=11720.013671875&y=16441.4443359375

3
Arctic sea ice / Re: The 2019 melting season
« on: June 22, 2019, 05:26:54 PM »
Included is a 20 hour loop showing the impressive ridge.  As energy rotates around it, it will go through several anticyclonic wave breaks (evident already).  These often give numerical models difficulty.  As they "break" they generally result in a cyclone downstream, in this case the Beaufort/CAA region.   Again, very hard to predict, and should give anyone pause about buying model runs beyond hour 120, and temper expectations.  Just my two cents.  I'll go back to simple observations of interesting features.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=1&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=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_m08&x=13964.6669921875&y=16288.22265625

4
Arctic sea ice / Re: The 2019 melting season
« on: June 22, 2019, 08:17:47 AM »
Mouth of the Kolyma.  More cracks forming, more signs the immobile ESS ice will disintegrate shortly.

5
Arctic sea ice / Re: The 2019 melting season
« on: June 22, 2019, 08:01:58 AM »
54 hour loop of the Laptev.  It's been pretty sunny there, a little burst of southerly winds today nudging the ice north.



6
Arctic sea ice / Re: The Rammb Slider Thread
« 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

8
Arctic sea ice / Re: The Rammb Slider Thread
« 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.

9
Arctic sea ice / Re: The 2019 melting season
« on: June 20, 2019, 10:17:34 AM »
East Siberia.

Looks like the fast ice cracked here from the weight of the inland freshwater sitting on it.

I don't think the river is flowing onto the ice, I think it's completely melting it into open water, as the severed ice appears to be moving around freely.  More cracks are forming, feels like the ESS will really deteriorate very soon.

12
Arctic sea ice / Re: The 2019 melting season
« on: June 17, 2019, 12:52:36 PM »

P.S. does anyone know the meaning of the LIGHT blue line in the Slater graph? I have already asked previously in the 'stupid questions' thread and nobody answered there.

I'd love to be corrected if wrong, but my understanding is that the light blue line treats the ice anomaly as a whole, whereas Slater looks at each grid cell independently.  But I could be misunderstanding.

Unrelated, here is the last week in the Beaufort blender.

Requires a click

14
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: June 15, 2019, 07:53:41 PM »
Slater model suggests sea ice is moving from where it's hard to melt, to where it's easy to melt. 



19
Arctic sea ice / Re: The Rammb Slider Thread
« 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.

20
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: June 13, 2019, 08:56:41 PM »
 :o

22
What does the team make of the latest NWS ice map?

I think the winds made a good run at closing it back up, but fell short, at least so far.  The pack becoming more disperse is allowing the complex currents to reveal themselves.  I'd say a non icebreaker can still safely navigate, but others may have a different opinion on what's considered open.

Contrast boosted for detail

23
Arctic sea ice / Re: The Rammb Slider Thread
« 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

25
Arctic sea ice / Re: The Rammb Slider Thread
« on: June 13, 2019, 04:14:49 AM »
Amazing animation.
So does the dark color represent wet surface or warmed surface?

I believe band M8 is considered to be in the near infrared spectrum, so it's possible that's is sensitive to surface temperatures, but as it is called the "cloud/snow" band, it's also possible is picking up on some property of wet snow.  Maybe some of both.  My hunch is that it's the snowpack "ripening", right at the threshold of melting.  So perhaps it's sensitive to temps near 0°C, or dampness, but I can't say for certain.  Only thing that I'm sure of, is that's is picking up on something.   :)  sorry I can't be more informative..

26
Arctic sea ice / Re: The Rammb Slider Thread
« on: June 13, 2019, 03:52:09 AM »
Greenland, band M8.
Needs click

29
Arctic sea ice / Re: The 2019 melting season
« on: June 12, 2019, 08:58:26 AM »
The Laptev is going to take it on the chin.  Look at those closely packed isobars, latest euro continues the push towards the Atlantic with the 970s cyclone, while keeping the Siberian side toasty.  The Beaufort low might pump some warmth into the CAA as well, as it stirs up the Beaufort sea, trading surface melt for bottom. 



30
Arctic sea ice / Re: The Rammb Slider Thread
« on: June 12, 2019, 03:04:41 AM »

31
32 hour loop, the frontal passage and associated wind shift is quite evident, it also removes all doubt from my mind that it's clear sailing for a non-icebreaker.

How do you make a loop with the stills filtered out? On ezGIF?
No filter,.I omit the frames when the satellite doesn't image the area by taking screenshots, it's a bit tedious, but makes for a better finished product in my opinion.

32
32 hour loop, the frontal passage and associated wind shift is quite evident, it also removes all doubt from my mind that it's clear sailing for a non-icebreaker.



34
18:22 UTC

Is it?

I think that front blew a path through the slush, but until all the clouds clear, can't be 100 percent positive.  There's a real chance the winds blow the pack back in, and I'm not sure if that would nullify any "open" path.   I'll let others decide.
2139Z

35
Arctic sea ice / Re: The 2019 melting season
« on: June 09, 2019, 02:44:18 PM »

I guess this illustrates a cold low over Beaufort and a warm low over Laptev (edit: warm front)
We should expect now some acceleration in area decline, compactness down. Beaufort is still cold but that low scattering the floes and stirring the preheated waters is slow bottom-melt slaughter we have seen other years.

I think there's still question as to how cold that Beaufort low will be.  Looking at 2m temps on the ecmwf, it appears the relatively long lived cyclone becomes fairly occluded, mixing out much of the cold surface air.

https://weather.us/model-charts/euro/north-pole-zoom1/temperature/20190614-2100z.html
This is roughly a 6 day loop, temp in celcius.


36
Arctic sea ice / Re: The 2019 melting season
« on: June 09, 2019, 12:24:52 PM »
Some fast ice is beginning to pulled away in the ESS. (First attachment,  band I1 with I3 overlay.
http://rammb-slider.cira.colostate.edu/?sat=jpss&z=4&im=18&ts=1&st=0&et=0&speed=120&motion=loop&map=1&lat=0&opacity%5B0%5D=1&opacity%5B1%5D=0.5&hidden%5B0%5D=0&hidden%5B1%5D=0&pause=20190609043123&slider=-1&hide_controls=0&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_i01&p%5B1%5D=band_i03&x=12211.4375&y=18844.78125


Second attachment is the EURO ensemble 5 day average sea level pressure. It screams slow extent loss.  Winds have reversed int the Chukchi already, and an amazing ice edge is visible inch thr RAMMB slider.  We should also see ice getting dispersed in the Beaufort for the time being.  The one constant is the push towards the Atlantic.  The ESS and Laptev will see persistent southerlies, and likely the most impressive extent declines.
  This isn't to say melting will halt, in fact, is should transport ice to areas it could melt quicker.  It'll be interesting to watch the floes reaction in the Chukchi in particular.



37
Cloud when you really don't need it.

Reminds me of Monty Python's "Total Eclipse of the Sun 1972".... "Rain... Rain".

I think we may get lucky and get some clearing around 15Z.

40
10 hour loop

41
Arctic sea ice / Re: Latest PIOMAS update (May 2019)
« on: June 05, 2019, 12:15:55 AM »
May PIOMASS thickness distribution falls short of being encouraging.

42
Arctic sea ice / Re: The 2019 melting season
« on: June 03, 2019, 12:29:24 PM »
925 Vector wind anomaly for May.

44
yup.  kinda stalled out there (animates on click)
Worldview images from consecutive days can be as little as 51 minutes apart or a much as 47.5 hours apart, it depends on which orbital swath the image was taken from.

If you look at it with sub daily imagery, it marches along unabated.
13.5 hour loop


45
Arctic sea ice / Re: The Rammb Slider Thread
« on: June 01, 2019, 10:27:48 PM »

I remember seeing little cyclonic features like that in 2013...14?

There was some discussion but no conclusions.

I suspect they are fairly common, but exist in the lowest part of the atmosphere along frontal boundaries.  Since they are so low, higher clouds likely obscure them normally.

Speaking of swirls, some neat, fractal-like ones in the Greenland sea today.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=5&im=18&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_i01&x=17694.875&y=13175.0419921875

Needs click, band I2, because it's the highest resolution.

46
Arctic sea ice / Re: The 2019 melting season
« on: June 01, 2019, 07:48:47 PM »
These large floes don't seem to have the strength like 2016 in the Beaufort.  I hope this isn't the thicker, multi year ice that's been discussed.

http://rammb-slider.cira.colostate.edu/?sat=jpss&z=5&im=18&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_i01&x=16862&y=20466

This was the largest chunk. (Requires a click)

48
14 hour loop, ending on June 1, 01 UTC

49
Arctic sea ice / Re: The Rammb Slider Thread
« on: June 01, 2019, 12:03:45 AM »
Plenty of streaks showing NE of Utqiagvik.
Band 8, needs click.

50
12 hour loop.

Pages: [1] 2 3 ... 9