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Messages - uniquorn

Pages: [1] 2 3 ... 5
1
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: March 18, 2019, 12:59:47 PM »
Seemed like a good day to go historical. Here is worldview Terra/Modis, least cloudy days between mar16-20, 2000-2019.

2
Arctic sea ice / Re: The 2019 melting season
« on: March 17, 2019, 12:51:33 PM »
http://polarportal.dk/en/sea-ice-and-icebergs/  ice surface temperature for the last freezing season (for reference)

3
Arctic sea ice / Re: The 2018/2019 freezing season
« on: March 15, 2019, 08:22:45 PM »
Mercator 0m salinity, jan1-mar14, used here to show current and possible upwelling along the Alaskan coast from Chukchi to Beaufort.
Worldview viirsbt15n, mar10-14 confirming.
FOOW warm water coming back up to haunt us perhaps

edit: forgot salinity scale

4
Arctic sea ice / Re: The 2018/2019 freezing season
« on: March 15, 2019, 02:06:50 PM »
On the more optimistic side, large floes are finally compacting into NE Svalbard. They have a few days before the wind changes to make an attempt at fast ice.

Worldview, viirsbt15n, atlantic front, mar7-15, ascat mar7-14 inset.

A tiny chip off the Nares polynya, bottom left (see https://forum.arctic-sea-ice.net/index.php/topic,2592.msg192004.html#msg192004)

5
Arctic sea ice / Re: The 2018/2019 freezing season
« on: March 14, 2019, 02:29:41 PM »
Comparison of ascat with cs2smos merged sea ice thickness for mar10. (8bit colour for the animation)
Cryosat2 not impressed with the old ice near FJL/SZ.

6
Greenland and Arctic Circle / Re: Old ice moving through Nares Strait
« on: March 12, 2019, 09:45:03 PM »
Slowpoke could well be a resident for quite some time. I had trouble finding the disparate matched pair but I think I identified the remnants. Worldview, mar7-12.

7
Arctic sea ice / Re: The 2018/2019 freezing season
« on: March 10, 2019, 11:08:13 AM »
amsr2, okhotsk, mar1-9. I hadn't noticed that warm spot in the middle before. Freezing is occuring some distance from the coast, probably due to upwelling as the fairly constant northerly winds have been cold. Or perhaps the freeze just struggles to keep up with the drift, see worldview https://go.nasa.gov/2J2dxab

added worldview, terra modis, feb10-mar10
I think this animation is typical of sea ice formation in rough seas, something we will probably see a lot more of next year freezing season on the eurasia side of the arctic. https://en.wikipedia.org/wiki/Sea_ice#Formation
Quote
In rough water, fresh sea ice is formed by the cooling of the ocean as heat is lost into the atmosphere. The uppermost layer of the ocean is supercooled to slightly below the freezing point, at which time tiny ice platelets (frazil ice) form. With time, this process leads to a mushy surface layer, known as grease ice. Frazil ice formation may also be started by snowfall, rather than supercooling. Waves and wind then act to compress these ice particles into larger plates, of several meters in diameter, called pancake ice. These float on the ocean surface, and collide with one another, forming upturned edges. In time, the pancake ice plates may themselves be rafted over one another or frozen together into a more solid ice cover, known as consolidated pancake ice. Such ice has a very rough appearance on top and bottom.
Though I think frozen sea spray may also play a large part in the cooling process.

8
Arctic sea ice / Re: The 2018/2019 freezing season
« on: March 04, 2019, 04:38:59 PM »
Mobile ice still struggling in the warm current north of FJL despite the cold air temperatures.
Worldview, viirsbt15n, feb12-mar4   https://go.nasa.gov/2IRqsvl

9
Greenland and Arctic Circle / Re: Old ice moving through Nares Strait
« on: March 02, 2019, 10:58:37 PM »
Shame about the clouds but it is possible to follow the floes down the strait and it is quite a race. I hope I have identified the stragglers correctly.
Worldview viirsbt15day feb27-mar2

10
Arctic sea ice / Re: The 2018/2019 freezing season
« on: March 01, 2019, 12:46:33 PM »
ascat and amsr2-uhh sep17-feb28.

11
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 27, 2019, 11:03:23 PM »
thanks johnm33

<>Does anyone have any idea how this extra heat and volume will dissipate ?
Probably not but as we're on the cusp of the freezing/melting season here are some options....

1. It's a 'one off' that slowly fades away by mixing, adding to general AGW.
2. It's perennial and layer thickness and temperature increase yearly, eventually warming surface layer and reducing ASI.
3. Without the thick ice 'governor' the gyre spins up to unstable speed, the freshwater layer slips off into the CAB at the end of the melting season and freezes in place up to 20m thick. The warm layer radiates into space in clear skies and gives us another 10 years to save the planet. Marvel make a film about it. ;)
4.....your own wild guess
didn't mean to imply your ideas were wild Bruce Steele


edit: incoming from bering/chukchi or upwelling?
Worldview, terra modis, Beaufort feb27

12
Arctic sea ice / Re: Guess the date of the max
« on: February 27, 2019, 01:05:43 AM »
I hope the logic works out oren, but the first 10 days of those 21 don't look too promising.
Windy ecmwf temperature forecast feb27

13
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 26, 2019, 10:07:21 PM »
A closer look at floes attempting to approach Svalbard, feb25-26 (some clouds)

14
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 26, 2019, 09:27:38 PM »
Mercator model doing quite a good job matching 34m temperature to Suomi npp/viirs on the atlantic side, feb26.

15
Arctic sea ice / Re: The 2018/2019 freezing season
« on: February 24, 2019, 11:29:55 PM »
uni-bremen smos is helpful for comparison of peripheral ice thickness up to 50cm. Here is 2011-2019 for feb23.
https://seaice.uni-bremen.de/data/smos/png/

16
Arctic sea ice / Re: The 2018/2019 freezing season
« on: February 23, 2019, 12:28:20 PM »
With the sun coming up over the Kara sea here is the Vil'kitskogo Strait (from Kara to Laptev) through clouds, feb9-22. Worldview viirsbt15day. https://go.nasa.gov/2IxB5DF

17
Arctic sea ice / Re: The 2018/2019 freezing season
« on: February 22, 2019, 11:41:49 AM »
Thanks Oren. Would probably only get 2/10 for including summer and no land mask.  ;)
amsr2-uhh, peripheral seas, dec1-feb21.

edit: It may be a very short freezing season for the Bering sea.

18
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 21, 2019, 12:16:15 AM »
johnm33, agreed about the changes from below. The results of the last cool(ish), cloudy summer probably confirm that. At what speed do the waves in the deeper layers travel?
Yes, I noticed those bumps at the bottom, though quite often they are smoothed. I'll run the numbers on 104 and 105 and see if I can line them up meaningfully.

Posting the following mp4 to show how inaccurate the previous attempts at bouy locations may be. I took less care to line them up this time as the projection is clearly wrong. The background is quite good though. I think octave does plot polar stereographic projection, struggling to find out how.


19
Arctic sea ice / Re: The 2018/2019 freezing season
« on: February 20, 2019, 09:59:45 PM »
<snippage>
Technical note: uniquorn has expressed interest in doing up the interferometry on the 8 previous years so the steps are explained one by one at DevCorner. The degree of difficulty here is about 3 on a scale of 10. <snip>
https://forum.arctic-sea-ice.net/index.php/topic,1259.msg143664.html#msg143664

Having taken a year to reach 'best efforts' production of difficulty 3/10 here are 339 days up to feb17. Quality has been sacrificed to keep size down to ~9MB mp4 though, in some ways, that helps when looking at the overall picture.
Quote
This amounts to land-masked framen of (R,G.B) = (dayn - dayn-1, dayn - dayn-2, dayn - dayn-3) - (50,50,50)) after contrast renormalization, adaptive histogram equalization and bicubic rescaling. In other words, it's plain gray when and where the ice isn't moving.
... and it's brighter (within the grey ice) when the ice is moving faster.
Note the movement along the interface of old/new ice and the surges towards the end in the Beaufort/Chukchi. Ascat images are affected by weather, particularly in summer, but the ice movement is still visible and it is valuable background information.
apologies in advance to anyone affected by flashing images
edit: no land mask as I think the weather effects over land are probably useful to some


 

20
Arctic sea ice / Re: The 2018/2019 freezing season
« on: February 18, 2019, 01:01:39 PM »
The only other thing I can think of (other than it being just a plain reading error) is maybe there were some anthropogenic discharges into the Tanana river upstream at Fairbanks which thinned the ice ?
Wild guess - permafrost depth, warmer river water?

Update on the big chunk in the Nares, now 2chunks, possibly more, jan15-feb18. The animation does cast some doubt on 3m ice in the Lincoln Sea. https://go.nasa.gov/2T2tII4

21
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 18, 2019, 12:42:02 AM »
An even rougher attempt at visualising whoi ITP107 . The charts are made using octave and I think they are accurate, though they need some tweaking, but scaling and alignment with ascat are by eye for now. Other ideas are in the pipeline.
It looks like itp107 is struggling a bit at the moment. Turbulence or lost its tether?

22
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 17, 2019, 11:11:12 AM »
An amateur attempt at visual identification of ice thickness using a comparison of ascat with an overlay of piomas thickness contours created using ImageJ edge detect for 2018.
Best efforts at scaling and alignment. Missing ascat days have been duplicated with nearest days. Poor data days remain for continuity. Off topic but posting here for reference.
thanks to wipneus, Zhang and Rothrock 2003 for piomas graphics and data

23
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 14, 2019, 11:25:02 PM »
update on ascat 2010-feb2019 for reference. (some gaps in data)
How to quantify mobility?

24
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: February 13, 2019, 07:35:12 PM »
Looking back using uni-bremen smos to see how it showed the flow from Nares into Baffin, may2010-feb2019

25
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 12, 2019, 07:13:46 PM »
update on mercator 34m salinity sep2017-feb2019. (scale same as previous post)

26
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: February 12, 2019, 12:33:34 PM »
update on mercator 0m salinity jul2017-feb2019.
Still wondering about the Lincoln Sea so here is CAA enlarged and speeded up to highlight long term movement.(same dates)

27
Arctic sea ice / Re: The 2018/2019 freezing season
« on: February 10, 2019, 10:05:30 AM »
A comparison of Bering sea ice from 2015-2019, jan1-feb8 using ImageJ edge detect on amsr2-uhh. Some lower concentration data has been removed to clean up the animation so this should only be seen as a guide.

28
Arctic sea ice / Re: The 2018/2019 freezing season
« on: February 06, 2019, 02:26:22 PM »
amsr2-uhh, atlantic front, jan11-feb5.
Polarview, between Svalbard and FJL, feb5
No predictions  ;) edit: Well, perhaps a smaller contribution from Kara to the CAB as the year goes on. That possible up or downwelling north of Svalbard is starting to look very persistent.

29
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: February 06, 2019, 01:56:46 PM »
A second opinion from worldview,viirs,bt15,night, feb5-6. Probably some serious grinding. Are there any sound recordings from the Nares Strait?
Close up courtesy of polarview, feb5

30
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: February 04, 2019, 02:32:38 PM »
Probably not bouncing as all the 'loose' ice in the Lincoln sea moves north from feb3 to feb4.
Interesting that the fast ice in the strait is disturbed in two places near to large slow moving floes.

edit: Perhaps being affected by weather further north (second image) and west, though it is too cloudy to see much.

added ascat, jan14-feb3.

31
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: February 02, 2019, 01:50:19 PM »
Rebound suggests the stuck floe has depth and has slowed shallow current into the Nares. Maybe some back pressure but probably wind causing the rebound. The image above was a lucky catch as worldview has since replaced it with a slightly clearer view and it does indeed just look like slowdown.
Enhancement doesn't offer too much more information though brightness temperature suggests the floe is thicker in places. The weaker sides that might have fractured are being compressed, the eastern side looking weakest. Some surface current is visible down stream on both sides, more on the west, probably refreezing meltwater. A bit odd as I think the strait is shallower on the west. Probably a healthy current at depth as floes downstream are moving quite rapidly.
Meanwhile upstream the ice is thickening, hopefully :)

edit: unless it's thinned overnight on the western side. In which case I may still be in with a chance....

32
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: February 01, 2019, 09:06:43 PM »
A small rebound behind the stuck floe. It's not looking too good for my bet (but maybe better for the ice)

33
Arctic sea ice / Re: The 2018/2019 freezing season
« on: January 30, 2019, 01:06:58 PM »
A queue forming in the Nares as a roughly 15km floe scrapes past the Petermann. That must be amazing to see on the ground. How to calculate roughly the volume of -0.5C water to melt a floe, say 15km square, 2m thick?
Big Chunk has released the nacelle section (she canna take no more capn).
Inset right shows mist (I think) clearing off the Petermann Gletscher where the area of a possible future calving (circled) is just visible in the last frames.
see Tealight, https://forum.arctic-sea-ice.net/index.php/topic,53.msg187370.html#msg187370

edit:forgot dates
worldview, viirs,bt15n, nares, jan28-30

34
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: January 29, 2019, 07:49:18 PM »
Tracked the north Greenland dark line back to nov17 using worldview viirs brightness temperature (band15)night. Posting here as it's 6MB. There are many other parallel fractures heading towards the Fram Strait and some larger ones out of crop on the Beaufort side of the Lomonosov. Possible they are related to the ridge. I don't know why this one stands out so clearly.
With a clear line to focus on, it looks like a lot of ice melted and exported.

35
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: January 29, 2019, 02:26:35 PM »
Bit the bullet and went back to november to look at surface current. Too cloudy before that.

36
Arctic sea ice / Re: The 2018/2019 freezing season
« on: January 29, 2019, 11:06:51 AM »
With the january poll deadline coming up, here are a couple of seas not fully included in Aluminium's regular postings.
Worldview, terra modis, bering, jan28
amsr2-uhh, baffin etc and okhotsk, jan23-28.

37
Arctic sea ice / Re: The 2018/2019 freezing season
« on: January 28, 2019, 09:15:36 PM »
Next big chunk nearing the Fram Strait might block it. Or just shatter and do nothing.Who places the bets here? ;)
I'll take a sportsman's bet on the big chunk at the entrance now. That it makes it down the strait.
and think about the one after that....

Laymans explanation: Some pressure differences often mentioned on this forum mean that water nearly always flows from Lincoln to Baffin. Water from 100m depth or more may always have been forced close to the surface at the entrance to the Nares but this year the ice is thinner and perhaps more importantly, younger. It behaves in the way shown in this and previous animations, which show it better than I can describe in words.
Temperature difference is over 34C between ice and ocean at surface, air temperatures reportedly -30C or less for weeks but the ice still breaks up. Conclusion is that a lot of probably -0.5C or warmer water is weakening the ice from below.

Yesterday big chunk was weakened at the front and lost its rear right end due to collisions.
Today it lost its rear left and its front right wing, but it is more streamlined for the journey ahead.

https://go.nasa.gov/2UukbqH
edit: corrected Kelvin temperatures

38
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: January 27, 2019, 08:16:42 PM »
More related fractures appearing further north in the Lincoln sea, jan26-27
Worldview, viirsbt15, green and rainbow

Comparison with feb3 2018

39
Arctic sea ice / Re: The 2018/2019 freezing season
« on: January 26, 2019, 06:03:20 PM »
It's quite difficult to track individual ice features from freezing season to freezing season but I was curious about a dark line on ascat which also shows up on worldview viirs.
The first animation is ascat 2018074(mar15), 2018317(nov13) and 2019025(jan25).

During the 2017/18 freezing season what was left of the Wrangel arm rotated clockwise to the border of the ESS and the Laptev and some thick ice in the Laptev ended up close to Severnaya Zemlya, shown in the first frames.

In the Nov13 frame the rotation continues and the forked shape of the older ice can just about be identified, somewhat distorted. Unfortunately, surface melting during the summer gives the ice a scatter whitewash as far as ascat is concerned.

In yesterdays frame it is the dark line north east of Kap Morris Jessup that interested me. It appears to be related to the dark line of possibly lower concentration ice between the 2 features in the first frame.
The worldview ani is just to confirm the existence of the darker line and hopefully some thicker ice coming up north of Greenland.



40
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: January 25, 2019, 10:33:16 PM »
worldview jan21-25

41
Arctic sea ice / Re: What's new in the Arctic ?
« on: January 25, 2019, 07:04:20 PM »
Speaking of hotspots (and forgive me if I missed it elsewhere - I'm brand new here):

What's up with this SST hotspot off Svalbard (and its little brother to the east)...?  18.5 C ... I wouldn't even need a wetsuit...!

I took this shot off null school out of curiosity over 3 weeks ago, and it's still there.  Is this normal?  An upwelling?  Volcanic?  Super curious.
It's warm, but probably not that warm. Thread about it here https://forum.arctic-sea-ice.net/index.php/topic,2194.msg134595.html#msg134595

42
Arctic sea ice / Re: The 2018/2019 freezing season
« on: January 25, 2019, 03:27:42 PM »
Worldview update on the Lincoln Sea with a bathymetry map from noaa. https://go.nasa.gov/2UgJYSV
Guess A: Some of the Atlantic water travelling south along the Lomonosov ridge heads south west at the Lincoln Sea, maintaining some of its southern momentum with a slower eastern momentum, but that is 'uphill' from depth.
Guess B: Water from the Beaufort side of the ridge as suggested by the later images.

A, B, both or neither?
worldview, lincoln sea, viirsbt15n, jan19-25 and noaa bathymetry map (2MB)
edit: added noaa scale

43
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: January 24, 2019, 05:42:54 PM »
A bit off topic, but perhaps relevant to Lincoln/Nares at the moment.
A basic map of Arctic ocean currents, though it is more complex at different depths when looking in more detail.
edit: not sure I even agree with that since it appears to have the Beaufort gyre going anticlockwise.
edit2: This one looks better from Robert Newton, Columbia university
edit3: Prefer this from Rebecca Woodgate for atlantic circulation

44
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: January 23, 2019, 11:15:13 PM »
Adding my theory that belongs to me about the Lincoln sea here, updated to jan23. (but it could be the super blood wolf full moon)
Worldview, viirs, bt15n, jan14-23 with NOAA bathymetry map.
will it go beyond the channel?

45
Arctic sea ice / Re: The 2018/2019 freezing season
« on: January 22, 2019, 02:47:54 PM »
Freezing season isn't over yet ;)
A rough comparison of ascat and piomas, mar15-jan21, weekly (best efforts matching the dates) piomas only up to dec15
Thanks to wipneus, Zhang and Rothrock for piomas
edit: reposted as 8bit and replaced missing frames, 3MB, better colour representation on forum and date matching is better now For best results please download the animation


Some of the detail is lost in a weekly animation but most here will remember that a significant amount of the last of the MYI was pushed into the CAA. What little was left has been spread along the CAA and into the Beaufort.
Added latest cryosat for reference. Note that the cryosat footprint is small and the ice these days is very mobile, particularly in the Beaufort.
Postgrads or keen number crunchers looking for ideas might try cross referencing cryosat swaths with osisaf ice drift. That would be nice.

Ice Shieldz, please see the Nares thread, https://forum.arctic-sea-ice.net/index.php/topic,176.msg186710.html#msg186710

46
Arctic sea ice / Re: The 2018/2019 freezing season
« on: January 20, 2019, 05:05:05 PM »
Here is a black and white version of my post above.
I found the colour one easier to understand and yes, a lot of older ice has been exported via the Fram Strait (or melted on the atlantic front before it got there). The Nares Strait is also still open.
We are increasingly dependant on the resilience of first year ice.
ascat, sep11-jan19, every 4 days (6.3MB)

The ice front approaches Svalbard again today.
polarview, jan20

47
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: January 18, 2019, 05:07:33 PM »
Update on the whoi ITP buoys. http://www.whoi.edu/page.do?pid=163197
ITP103 still showing an increase in salinity at depth
ITP104 little change
ITP105 is reporting again :)  The data may need smoothing.
Both 104 and 105, most northerly, are drifting  further north against the annual drift.
ITP107 decrease in salinity to >50m confirming gyre
ITP109 decrease in salinity to ~50m confirming gyre. 50m-100m warm layer
ITP110 confirming 50m-100m warm layer

argo float 3901910 state is inactive  :(

48
Arctic sea ice / Re: The 2018/2019 freezing season
« on: January 17, 2019, 04:57:26 PM »
Beaufort working up quite a spin over the last two weeks.
Worldview viirs, bt15n, jan4-17  (3.3MB)  https://go.nasa.gov/2TTrPdG

49
Arctic sea ice / Re: The 2018/2019 freezing season
« on: January 16, 2019, 02:27:37 PM »
A further look at the amsr2 representation of ice on the atlantic front over the last few days where refrozen fractures show as higher concentration than older floes. This is apparent on both uni Hamburg and Bremen.
Comparing with worldview viirs, brightness temperature(band 15,night) with different palettes (green1 and rainbow1) there is a haze above the refrozen fractures, more visible on the rainbow palette. Perhaps it is mist due to heat escaping through the thinner ice. Snow would be unlikely where the ice meets the ocean.
worldview,viirs,bt15n,jan16  https://go.nasa.gov/2TWCNzh
amsr2-uhh, jan15 - high contrast on right

edit: added polarview image for reference, nw of FJL, jan18

50
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: January 16, 2019, 01:23:15 AM »
This animation is so messy that I wasn't going to post it, but I think it shows how volatile ice extent/area is over recent years, particularly when the peripheral seas are freezing.
amsr2-uhh, dec1-jan13 from 2015/16-2018/19

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