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Messages - uniquorn

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2601
Arctic sea ice / Re: The 2018 melting season
« on: April 28, 2018, 10:41:28 PM »
The ice close to CAA and the string of floes making their way round the Beaufort are MYI. I'm not sure how much of the rest is.
Ascat melting season day78-116.
(hopefully one of us will volunteer to check ascat every day)

technical notes:
imagej: brightness/contrast 43,255 (some loss) CLAHE 63,255,2.2
gimp: duplicate last frames, scale to 700, delay 250
thanks to A-team for graphics tips

2602
Arctic sea ice / Re: The 2018 melting season
« on: April 28, 2018, 09:33:22 PM »
uni-hamburg amsr2 and dmi ice temperature for the current melting season Mar21-Apr27

2603
Arctic sea ice / Re: The 2018 melting season
« on: April 28, 2018, 04:18:41 PM »
With warm winds forecast for the Greenland sea next week, an animation for Baffin and Greenland seas for this melting season with yesterdays worldview for comparison.

uni-hamburg amsr2 ice concentration for Baffin and Greenland seas Mar21-Apr27.
Worldview terra/modis apr27

2604
Arctic sea ice / Re: The 2018 melting season
« on: April 28, 2018, 03:03:59 PM »
Two animations of worldview (satellite) and Norwegian Met Ice charts, show that the open water to the north of Svalbard has decreased in size between 17 and 26 April.
This may seem contrary to the images posted by Uniquorn earlier - but such are the vagaries of ice movement/export.
Sorry if my images gave that impression. I thought amsr2 clearly showed the ice front moving toward Svalbard.
The worldview animation was to track the plucky flow which zoomed around the 'killing ground', though it does also show the speed at which individual floes are melting.
Here is a closer look from amsr2 uni-hamburg for this melting season.

2605
Arctic sea ice / Re: The 2018 melting season
« on: April 25, 2018, 08:59:20 PM »
I wasn't going to post amsr2 of the atlantic side but do so in memory of the plucky floe that almost made it across the nth of Svalbard 'killing zone' earlier this month.
Worldview confirms the attempt in the second animation (marked with an X in the first frame). Interesting to see how fragile the refreeze between the floes is in this area.

uni-hamburg amsr2 ice concentration for kara and barents Mar21-Apr24
Worldview terra/modis mar28-apr9

2606
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: April 25, 2018, 08:22:23 PM »
thank you Gerontocrat

2607
Arctic sea ice / Re: The 2018 melting season
« on: April 25, 2018, 07:29:14 PM »
With even more warm temperature anomalies forecast over bering and chukchi for the next few days, an animation of amsr2 for this melting season.

Light blue areas normally indicate lower concentration but may also be due to cloud cover (imho).

uni-hamburg amsr2 ice concentration for bering and chukchi Mar21-Apr24.

2608
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: April 25, 2018, 06:55:31 PM »
Quote
Melting (and the reverse) seems to go in waves
Your chart clearly shows a (possibly random) wave pattern. Does the area chart show a similar pattern? It may be that the way extent is measured/calculated amplifies the waves.

2609
Arctic sea ice / Re: The 2018 melting season
« on: April 25, 2018, 04:07:48 PM »
With more warm temperature anomalies forecast over ess and laptev for the next few days, an animation of amsr2 for this melting season with today's worldview for comparison.

uni-hamburg amsr2 ice concentration for ess and laptev Mar21-Apr24.
Worldview terra/modis apr25

 

2610
Arctic sea ice / Re: The 2018 melting season
« on: April 24, 2018, 08:44:47 PM »
With favourable weather (for viewing) north of Greenland yesterday I thought I'd try to find visible signs of thicker ice north of the 'Kara tongue' using viirs. An ascat image of the 'Kara tongue' export is shown inset on the first two frames. I've squashed the palette in each zoom of the viirs image as far as possible to show detail around the boundary while minimising artifacts.
Not very conclusive, but the area on the left of the last frame does appear to show longer cracks and less refrozen fractures. Hopefully the ice is a bit thicker there.

ascat apr23
worldview terra/modis, viirs brightness temperature band 15, progressively squashed palette apr23

2611
Arctic sea ice / Re: The 2018 melting season
« on: April 19, 2018, 01:08:45 PM »
Beaufort Apr16-18 terra/modis with viirs for further detail.

2612
Arctic sea ice / Re: The 2018 melting season
« on: April 17, 2018, 04:54:29 PM »
Fram Strait and Svalbard Apr13-17.
Ice from the 'Kara tongue' (top left) doesn't last long as it meets the atlantic front. Warmer southerlies were accompanied by cloud cover, pushing back the ice front nearer Greenland with another small lift off from the fast ice on the Nth Greenland coast.
Not much wind resistance anywhere, it seems.

Worldview terra/modis

2613
Arctic sea ice / Re: The 2018 melting season
« on: April 15, 2018, 10:22:18 PM »
It does look a bit challenged but I think other years have been worse.
worldview brightness temperature viirs band 15, night apr14

2614
Arctic sea ice / Re: The 2018 melting season
« on: April 15, 2018, 10:03:19 PM »
I read somewhere up thread that sea ice temperature may be as useful as air temperature for estimating increase in ice thickness but I found it difficult to visualise a daily animation  from DMI due to weather interference. A 10 day average makes it easier. Unfortunately data is missing from oct20 to nov23rd so I've repeated the two nearest frames.
Quote
At DMI, the temperature of the surface is not measured directly. Instead, observations are used from three infrared channels on the “Advanced Very High Resolution Radiometer” (AVHRR), which is on board the MetOp-A satellite. The instrument is unable to see through clouds, however. A statistical method is therefore used to provide the missing data. The edge of the ice is shown as a black contour line. It is defined by a sea ice concentration of 15%, i.e. 15% of the surface is covered by ice.

2615
Arctic sea ice / Re: The 2018 melting season
« on: April 15, 2018, 07:33:17 PM »
Floes in the 'Kara tongue' NE of Svalbard 'drifting to their doom'. Mostly first year ice held together with younger refreeze.

Worldview aqua/modis and VIIRS temperature brightness band 15, night

2616
Arctic sea ice / Re: The 2018 melting season
« on: April 15, 2018, 03:46:59 PM »
Chukchi yesterday and ascat animation jan-apr14.

worldview aqua modis
ascat:
ImageJ brightness/contrast 53-255,CLAHE 63-255-2.2
gimp duplicate final frame,scale 200% unsharp mask 5,0.5,0
(A-team tips)
edit:unsharp mask needs more work, went back to sharpen 50

2617
Arctic sea ice / Re: The 2018 melting season
« on: April 10, 2018, 09:44:32 PM »
Kara forked tongue. Ascat day40-98

Technical note:
ImageJ: adjusted brightness/contrast 23-255 (some loss), CLAHE 127-256-2.2
gimp: duplicate final frame, scale 200%, sharpen 60
thanks to A-team for tips on ascat graphics


2618
Arctic sea ice / Re: The 2018 melting season
« on: April 10, 2018, 07:03:07 PM »
Windy has ECMWF, but you can’t see high latitudes well because of the projection.
windy has a 3d mode in the menu

2619
Arctic sea ice / Re: Latest PIOMAS update (April update)
« on: April 10, 2018, 05:02:12 PM »
could be that SMOS takes longer to gather the data.

I think the CAA anomaly is due to persistant CAA export (aka garlic press) as well as temp, mobility etc.
Ascat ~Aug2016-Apr2018 (every 4days to reduce file size)
thanks to A-team for tips on ascat graphics

edit: some of that MYI may still be working it's way through to Baffin Bay.
edit: after looking again, some more MYI is making it's way around the Beaufort

2620
Arctic sea ice / Re: The 2018 melting season
« on: April 10, 2018, 02:32:50 PM »
Thanks Niall.
windytv displays ecmwf and gfs.
https://www.windy.com/?temp,76.568,14.854,4,m:fOAagpe

2621
Arctic sea ice / Re: The 2018 melting season
« on: April 10, 2018, 01:32:28 AM »
What's the verdict on GFS vs ECMWF?
I see your point. I picked a random spot but selecting a few locations nearby I get 3.6C to 6.4C just now.

2622
Arctic sea ice / Re: The 2018 melting season
« on: April 09, 2018, 09:34:49 PM »
Yes, nullschool forecasting winds over 5C close to Svalbard on apr13.

Update on Kara Sea. Apr5-9 (worldview)

2623
Arctic sea ice / Re: Latest PIOMAS update (April update)
« on: April 09, 2018, 08:10:59 PM »
Thank you seaice.de.
That does not look good. All the positive anomalies are in areas that are likely to melt out.

2624
Arctic sea ice / Re: The 2018 melting season
« on: April 08, 2018, 02:56:19 PM »
A closer look at Mackenzie Bay, Beaufort Sea yesterday. A nice example of refreeze and ridging. Temperature ~-19C

Worldview Terra/Modis

2625
Arctic sea ice / Re: The 2018 melting season
« on: April 07, 2018, 04:14:25 PM »
Kara Sea has largely avoided this years warm weather events but, as highlighted by Neven up thread, is getting some more challenging weather today and tomorrow.

Worldview terra modis apr5 (last clear day)
Nullschool forecast.

2626
Arctic sea ice / Re: The 2018 melting season
« on: April 06, 2018, 10:33:48 AM »
The sea of okhotsk bringing extent down.

2627
Arctic sea ice / Re: The 2018 melting season
« on: April 05, 2018, 11:58:24 PM »
That looks like a bit of refreeze along some of the chukchi coast today

Worldview TM

2628
Arctic sea ice / Re: The 2018 melting season
« on: April 05, 2018, 12:36:16 AM »
North of Svalbard 2017-06-25
Will have to wait a bit longer this year.

2629
Arctic sea ice / Re: The 2018 melting season
« on: April 04, 2018, 09:35:19 PM »
Beaufort Sea Mar29 from 2000-2018. (VIIRS only available for 2018)

Hopefully not too historic to be off topic. Some clouds but good enough for comparison

2630
Arctic sea ice / Re: The 2018 melting season
« on: April 04, 2018, 08:27:53 PM »
Bering may hold out a little longer. The wind has changed again.

2631
Arctic sea ice / Re: The 2018 melting season
« on: April 04, 2018, 07:53:18 PM »
The Sea of Okhotsk was one of the big extent fallers yesterday.

Worldview today and Uni-Hamburg amsr2 Jan-Apr3


2632
Arctic sea ice / Re: Latest PIOMAS update (April update)
« on: April 03, 2018, 06:06:30 PM »
March 2017 had (very approximately) three times the Fram export of ice that of March 2018.  (January and February had vaguely similar export amounts this and last year.)
Yes. Not much MYI this year.

2633
Arctic sea ice / Re: The 2018 melting season
« on: April 03, 2018, 02:54:53 PM »
I expect sea surface temperature and wave action doesn't help.
Nice view on Worldview today

Terra Modis

2634
Arctic sea ice / Re: The 2018 melting season
« on: April 03, 2018, 12:55:36 PM »
It won't be long ebefore the last ice in the Bering Sea gives up the ghost, and the Chukchi Sea doesn't look good. A lot of the ice there must be pretty thin, given that there was open water and sub 0.5m ice only 6 weeks or so ago
Also to factor, we are with in a week or so of reaching "break even" where incoming insolation will balance outgoing long wave radiation from the top of the atmosphere.  The current predicted spasm of inflowing heat will only exacerbate the problem.
Agreed. Bering/Chukchi Jan-Mar29
amsr2 uni-hamburg

2635
Arctic sea ice / Re: The 2018 melting season
« on: April 02, 2018, 07:22:08 PM »
Winter-to-summer transition of Arctic sea ice breakup and floe size distribution in the Beaufort Sea
https://www.elementascience.org/articles/10.1525/elementa.232/

Thanks for this Archimid.
For those who don't have time to read the link. c1 to c4 on the charts are the 4 clusters of buoys. w1 to w7 are wind events.

2636
Arctic sea ice / Re: The 2018 melting season
« on: April 02, 2018, 02:34:00 AM »
Yes, beaufort looks bad. Look forward to Jayw next update.
I did a quick reality check on Chukchi going back to 2004. Some clouds, but good enough for comparison.

Worldview Terra/Modis (some differences pre2013)

2637
Arctic sea ice / Re: The 2018 melting season
« on: April 01, 2018, 06:30:11 PM »
Chukchi Sea Mar23-Apr1

Worldview Terra/Modis

2638
Arctic sea ice / Re: The 2018 melting season
« on: March 31, 2018, 07:29:58 PM »
A partially refrozen lead in the Svalbard and FJL area. Probably not significant yet. Nullshool has temperature <-20C so it should freeze over completely. Mar31

Worldview Terra Modis

2639
Arctic sea ice / Re: The 2018 melting season
« on: March 31, 2018, 04:59:42 PM »
Sorry.

The first few frames of large mp4's play and then I get a video stopped loading error:). They run ok when I download them.

2640
Arctic sea ice / Re: The 2018 melting season
« on: March 31, 2018, 03:05:20 PM »
The first few frames of large mp4's play ad then I get a video stopped loading error:). They run ok when I download them.

Lovely view of the Sea of Okhotsk today on Worldview. A few days of warmer weather forecast.

2641
Arctic sea ice / Re: The 2018 melting season
« on: March 29, 2018, 10:11:24 PM »
I think the 'Greenland ratchet' is temporarily disabled.
Mar25-29
[edit]-just checked and there was similar movement in 2017, without the open water event.

Worldview viirs brightness temperature band15,night,squashed pallette

2642
Arctic sea ice / Re: The 2018 melting season
« on: March 29, 2018, 01:48:40 PM »
Whatever about the Siberian coasts, it could also promote more lift off in the eastern Beaufort (which has already begun !)
I was just looking at that. Beaufort is mobile despite low temperature anomalies. It will be interesting to see what happens with warmer weather forecast.
Mar18-28

Worldview brightness temperature,band15,night,squashed palette

2643
Arctic sea ice / Re: The 2018 melting season
« on: March 29, 2018, 01:17:53 AM »
Thank you for that correction Shared Humanity. I've edited the original.

dmi 80N temperature chart:



2644
Arctic sea ice / Re: Arctic sea ice minimum early prediction
« on: March 28, 2018, 08:41:08 PM »
My choice is founded on winter heat combined with current weakness in the Chukchi, the incredible vanishing Bering, the Svalbard gap, and general poor quality of ice in the Barentz and Kara.
Two years of really low Freezing Degree Days, record heat in the North-west Pacific, and continued inflow of warm Atlantic waters...
All the above and probable repeat of open water north of Greenland.

2645
Arctic sea ice / Re: The 2018 melting season
« on: March 28, 2018, 04:44:24 PM »
Clearer weather north of Greenland allows a decent view of the thinner ice that remains of the storm damage and the ice front expanding drifting into the Fram Strait. Mar25-28.

Worldview brightness temperature band 15, night squashed palette

2646
Arctic sea ice / Re: The 2018 melting season
« on: March 28, 2018, 01:36:05 PM »
Quote
which I have posted 30-40 times up-forum to no apparent effect

I couldn't resist a bit of humour and gained some ST lore.

Nonetheless, looking at the ascat sea ice roughness 01 Jan to 25 Mar 2018 above, accepting that the ice movement is largely rotational clockwise, there is a discernible export across the whole Atlantic front while losing ice cover on the Pacific side.
Largely wind driven recently and probably not what Bones implied.

2647
Arctic sea ice / Re: The 2018 melting season
« on: March 28, 2018, 02:18:00 AM »
As Bones would say, "it's transpolar drift Jim, but not as we know it...."

2648
Arctic sea ice / Re: 2018 Melting Season - Predictions and Speculation
« on: March 24, 2018, 09:48:53 PM »
Now, to seed the discussion;
[Edit:  I predict the "hole" north of Svalbard will not increase in size, but will persist as a killing ground for ice forced into it.]
I think the killing ground may be temporarily overwhelmed.


2649
Arctic sea ice / Re: The 2018 melting season
« on: March 24, 2018, 01:14:00 PM »
That didn't last long :-\

Worldview Bering Strait Mar16-23

2650
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: March 21, 2018, 06:58:31 PM »
It seems Bering has just almost made a new high, following Feb 7th which was at 411.5k, indeed a very strange year.
extent+lower volume=stranger+stranger ;)

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