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Messages - uniquorn

Pages: [1] 2 3 ... 49
1
Arctic sea ice / Re: Tides
« on: Today at 11:03:19 AM »
Understood, we disagree.  :) Thank you for accepting that there is some tidal movement. My interest is mostly at the shelf breaks, where that measly movement might be amplified by the rapid change in depth.

2
Arctic sea ice / Re: Tides
« on: Today at 10:17:18 AM »
mosaic buoys over the yermak plateau from the mosaic thread.

rammb of yermak/fram. I'm not claiming that is all tidal but similar movement suggest a tidal contribution.

3
Arctic sea ice / Re: Tides
« on: Today at 09:50:26 AM »
Wasn't this enough for 1)?
Perhaps JayW's gif, also northern Laptev, from jul19 2020 for 2)
Both already on this thread.

4
Arctic sea ice / Re: Tides
« on: Today at 09:24:30 AM »
In my humble opinion, mosaic buoys are showing tidal movement that affects melt. They have been showing it ever since the project started. Tidal movement is less detectable further north. Some people see it, some don't, and some don't want to see it.
The ICEX buoys may show it too when I zoom in on them later.

5
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: August 03, 2020, 11:20:51 PM »
update on rotation north of Lincoln. Here using worldview aqua and terra interleaved, jul21-aug3.
slight contrast enhancement.

Also posting some surface net downward shortwave flux differences for reference, 202006 minus 201206 to 201906. Note that the scale is -100to100

6
Arctic sea ice / Re: Tides
« on: August 03, 2020, 01:57:49 PM »
<>The tides are always there doing their bits with eddies and some fast ice breakup (e.g. in the CAA) but the ice north of Greenland does not melt and retreat north every summer.
I expect that shelf break melt will become a more accepted part of the melting season as the arctic moves to a higher percentage FYI. Without a constant supply of MYI, north of Greenland could start to look more like north of FJL/Svalbard, dependent on wind direction.
Unfortunately there is only a buoy swarm in the Fram at the moment. Most viewers will be able to detect non negligible tidal movement. For me this disproves the theory that tides just go up and down with a negligible tidal current that has no effect on ice. There is, to me, clearly a more circular motion involved, suggesting eddies and mixing that would affect ice melt, particularly at shelf breaks, where the underlying slope of the ocean floor likely amplifies the turbulence.
These buoys are over 250km from nearest land

shelf break image from http://mseas.mit.edu/Research/MOPE/index.html  (not arctic but shows some of the processes)

added gif from http://rob-hetland.blogspot.com/2005/04/shelf-break-front-simulation.html
Quote
Shelf break front simulation
Here is a sample cross-section from an idealized shelf break front simulation. The contours are salinity, the colorfill velocity.
This is exactly the kind of movement seen in the FJL/Svalbard gap.  click
rammb example here

7
Arctic sea ice / Re: The 2020 melting season
« on: August 03, 2020, 12:23:45 PM »
update on melt north of greenland using amsr2-uhh, jul26-aug2
chaotic mix of wind, currents and tides in the Fram Strait/Greenland Sea shown by mosaic buoy drift, jul20-aug3

8
Arctic sea ice / Re: The 2020 melting season
« on: August 03, 2020, 01:35:53 AM »
amsr2-uhh for 2012 is available from aug1. I tried hard to replicate this comparison of 2020 with 2012 but A-Team's is better. Passing it on unmodified.
Green is open water for both years
Orange, open water in 2020
Pink, open water in 2012.
pixel count overlayed onto greenland
click to run

9
Arctic sea ice / Re: The 2020 melting season
« on: August 03, 2020, 12:37:38 AM »
overlay of amsr2-uhh on to mercator(model) 0m ocean temperature. jul1-aug1. (9.5MB)

10
Developers Corner / Re: Test space
« on: August 02, 2020, 11:51:40 PM »
I don't think longer tails works so well. Drift can be abrupt and the tails soften it.
replaced with 02b
Possibility of comparing avgdriftspeed/wk/yr perhaps

11
Arctic sea ice / Re: The 2020 melting season
« on: August 02, 2020, 01:48:05 PM »
These thickness graphs, while useful, never have materialized in a complete meltout.
They might be more representative of the ice state than a one day difference image.

Here looking at the CAB 'decompacting' north of Laptev. Identifiable features drifting south while the ice edge stays relatively static.

12
Arctic sea ice / Re: The 2020 melting season
« on: August 02, 2020, 11:44:57 AM »
Animation of the development of low concentration ice and open water north of Greenland. amsr2-uhh, jul27-aug1

13
Developers Corner / Re: Test space
« on: August 02, 2020, 12:03:10 AM »
buoy ani test. probably better with slightly longer tails

14
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 10:53:12 PM »
Direct solar isolation  melt we have observed:
75-80N: as late as August  20th.
70-75N: end of August.
Solar daily radiation per week still around 75% 65% of peak at 80N

more cyclone damage in the beaufort. S1 yesterday.

15
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 08:30:32 PM »
https://go.nasa.gov/3hVyJLw  Slight contrast adjustment to help 'see through' the clouds

16
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 08:20:32 PM »
polarview S1 of the after effects of the brief low in the chukchi/beaufort, jul31

17
Arctic sea ice / Re: What the Buoys are telling
« on: August 01, 2020, 05:26:56 PM »
JAMSTEC/ICEX buoys currently in the Chukchi
Quote
About Warm Buoy & SideKick

JAMSTEC WARM (Warming and Irradiance Measurements) Buoy project has started to comprehend temporal changings of oceanic enviornment from ice-covered season toward open-water season. Thr WARM Buoy and Side Kick system (see below) was deployed at ICEX 2020 camp station in Beaufort Sea. These systems measure vertical structure of water mass (temperature and salinity) and chlorophyll-a fluorensence from surface to 60-m depth for every 1-hour and send via iridium satellite communication system (see real-time data page). SideKick monitors daily time series of upper-ice views (see gallery pages).
We kindly acknowledge US Navy Arctic Submarine Laboratory and Pacific Gyre Inc. for their kind support for this project. For your information, please also see UpTemp0 web site by University of Washington and WARM Buoy project of Old Dominion University.

Sidekick takes pictures :)
clear images from may1-jul26  click

18
Arctic sea ice / Re: The 2020 melting season
« on: August 01, 2020, 03:15:25 PM »
Overview of buoy drift in the Beaufort/Chukchi, then zooming in on that cluster of JAMSTEC/ICEX buoys currently in the Chukchi
Quote
About Warm Buoy & SideKick

JAMSTEC WARM (Warming and Irradiance Measurements) Buoy project has started to comprehend temporal changings of oceanic enviornment from ice-covered season toward open-water season. Thr WARM Buoy and Side Kick system (see below) was deployed at ICEX 2020 camp station in Beaufort Sea. These systems measure vertical structure of water mass (temperature and salinity) and chlorophyll-a fluorensence from surface to 60-m depth for every 1-hour and send via iridium satellite communication system (see real-time data page). SideKick monitors daily time series of upper-ice views (see gallery pages).
We kindly acknowledge US Navy Arctic Submarine Laboratory and Pacific Gyre Inc. for their kind support for this project. For your information, please also see UpTemp0 web site by University of Washington and WARM Buoy project of Old Dominion University.

Sidekick takes pictures :)

19
Arctic sea ice / Re: The 2020 melting season
« on: July 31, 2020, 11:18:02 PM »
I get that, but can you actually see it? or measure it? I picked one floe that was easy. Normally we see 'goodbye waves' but I assume some other process happens in open water in the 'crack'.

edit: ok. It was easy to fine 'glue ice' melting too.
I keep wondering how much of that ice is still MYI, and how much is FYI. MYI ice melts away from the top, and refreezes at the bottom. So how much of that MYI is really still MYI, and not FYI that was added through winter?
PMFBI and stating the obvious - I wonder this too. You can't always eyeball the 90% below the waterline.
In recent years MYI has drifted down the Nares and been 'pulverised'. A process that I think I understand. So far this year ice in the Lincoln Sea melts 'in situ' while possibly drifting west. But there are no 'goodbye waves' which can be seen further south in the Parry channel.

@weatherdude88 some neighbouring arctic seas

20
Arctic sea ice / Re: Off Topic
« on: July 31, 2020, 09:57:09 PM »
A graphic showing wind-driven ice movement
Ascat shows ice movement. It doesn't necessarily have to be wind driven. Fram Strait is a clear example.

21
Arctic sea ice / Re: The 2020 melting season
« on: July 31, 2020, 11:17:00 AM »
Whoi bouys show sustained bottom melt in the Beaufort at least to 75N.  They also show a quick spike in salinity the last couple days.  A sign of near surface overturning of the fresh water layer.
If that is the case the layer below it is torching.
Best not to read too much into the recent itp114 profile, both itp113 and 114 profilers have been stuck below 250m for the last few days due to high drift speed. More details here

22
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 30, 2020, 10:53:06 PM »
Good clear view north of CAA Greenland. Some contrast adjustments.
Signs of rotation in the middle just north of Lincoln
Following up on rotation north of Lincoln Sea

23
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 10:12:17 PM »
I get that, but can you actually see it? or measure it? I picked one floe that was easy. Normally we see 'goodbye waves' but I assume some other process happens in open water in the 'crack'.

edit: ok. It was easy to fine 'glue ice' melting too.

24
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 09:20:27 PM »
A casual look at the Lincoln Sea on worldview doesn't show much sign of melt but there is some kind of attrition going on. https://go.nasa.gov/33993H1, jul23-30

25
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 30, 2020, 08:15:56 PM »
whoi itp114 7-250m, a bit longer due to interesting profile change on day136.  Also a short ani of recent salinity down to 800m to show profiler struggling.
Thicker lines, bigger titles on these :)

26
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 30, 2020, 07:24:05 PM »
7m temperatures have been slowly rising since ~day170 (jun18). I think that is due to insolation.
During recent days the profiler has often been unable to rise above 250m, probably due to high drift speed. I don't know the reason for the recent drop in temperature at 5m, mixing down to 25m?

27
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 30, 2020, 04:14:11 PM »
Perhaps a separate thread for the utqiagvik webcam would be appropriate.

28
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 30, 2020, 03:42:45 PM »
As it happens, a new user just posted about the same buoys, see above.
Welcome, tobiasR.
Welcome indeed!

29
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 30, 2020, 03:18:04 PM »
Too salty? - Don't know. I find it difficult to interpret 0m salinity under ice and after seeing the Tbuoy data I'm not sure that much should be inferred from modelled data. That said, itp114 looks interesting recently, though data starts at 7m depth. Will check it out later.
image removed

30
Arctic sea ice / Re: Off Topic
« on: July 30, 2020, 01:53:20 PM »
for any feature to show means very deep disturbence Grakkel is about 3000m down but the area in question is opposite St. Anna.
Not dismissing the idea out of hand but it is a big ask from 3000m down. It's possible that there is turbulence along the Lomonosov anyway due to a (modelled) convergence of currents. Mosaic buoys saw evidence of turbulence further south.
Perhaps more likely is that the low concentration is caused by wind on the FYI/SYI boundary with the first year ice 'racing' ahead.

It's not clear what you were trying to show in the last ani. btw I hadn't realised we were travelling at the speed of sound.

31
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 01:22:02 PM »
My eyes insist that under the thick cloud bands (in Worldview) AMSR2 concentration is higher than elsewhere, thus my conclusion/suspicion that if anything, current concentration might be jacked up by such artifacts, rather than jacked down.
Agreed. amsr2 concentration is often represented as higher under cloud, so higher concentration streaks. It's the low radials that are the worry.
Nice images BFTV.

32
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 11:57:59 AM »
superimpose (and synchronize) the cyclone and the concentration images
I think amsr2 is representing the state of the ice quite accurately in this case.
click

33
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 11:18:46 AM »
A quick view, after the worst part of the storm...
uni-hamburg version, amsr2-uhh, beaufort-chukchi, jul18-29 
click

34
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 29, 2020, 11:50:55 PM »
amsr2-uhh view, jul21-28

35
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 29, 2020, 11:28:10 PM »
Westward motion is slowing. That floe must have landed gently on the tip of Axel Heilberg.
jul19-29

36
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 29, 2020, 11:01:26 PM »
beaufort/chukchi low for reference

37
Arctic sea ice / Re: What the Buoys are telling
« on: July 29, 2020, 10:27:07 PM »
Kept the drift speed in and added BP as label. At least one buoy has a faulty barometer but it has been left in to remind that representations of raw data need to be treated with caution.
It's possible that drift speed went higher during the gaps in the drift path.

38
Arctic sea ice / Re: What the Buoys are telling
« on: July 29, 2020, 09:25:12 PM »
Some have BP.

Quote
ITP117 was deployed on a 1.35 m ice floe in the Beaufort Sea on September 19, 2019 at 80° 55.0 N, 135° 31.9 W as part of the Beaufort Gyre Observing System (BGOS) during the JOIS 2019 cruise on the CCGS Louis S. St. Laurent. On the same icefloe, a prototype Tethered Ocean Profiler (TOP), and a US Army Cold Regions Research and Engineering Laboratory (CRREL) Seasonal Ice Mass Balance Buoy 3 was also installed. The ITP is operating on a standard sampling schedule of 2 one-way profiles between 7 and 760 m depth each day and includes a fixed SAMI PCO2 with ODO and PAR at 6 m depth.
This looks like the cryosphere simb sharing a floe with itp117

39
Arctic sea ice / Re: What the Buoys are telling
« on: July 28, 2020, 09:47:24 PM »
Tbuoy update. The red dot on the first ani is polarstern at 79.41N -2.72  at 0500UTC today. Not all Tbuoys are shown.
Temperature profile, jul1-27. Lots of melting.

40
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 28, 2020, 08:50:52 PM »
mercator salinity, 34m, mar21-jul27
best viewed at half speed

41
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 28, 2020, 12:02:20 AM »
Good clear view north of CAA Greenland. Some contrast adjustments.
Signs of rotation in the middle just north of Lincoln

42
Arctic sea ice / Re: The 2020 melting season
« on: July 27, 2020, 09:03:33 PM »
Atlantic waters north of Wrangel Island? In the Chukchi? Or the EES perhaps?
According to the mercator model salinity at 34m depth, here with amsr2-uhh overlaid at 60%, atlantic waters reach almost 80N of Wrangel Island before turning back and eventually reaching the Fram.

Last year, iirc, there was some anomalous melt in this area, possibly due to atlantic water mixing in the shallower regions or perhaps due to a 'pinch point'.

The salinity scale is not accurate with the overlay, but yellow > green > blue

43
Arctic sea ice / Re: MOSAiC news
« on: July 27, 2020, 07:14:10 PM »
Sea-ice extent in the Arctic at a historical low

Quote
Meanwhile, the Polarstern is currently in Fram Strait between Svalbard and Greenland. Prof Markus Rex, Leader of the MOSAiC Project and an atmospheric physicist at the Alfred Wegener Institute in Potsdam, is currently on board. As he reports: “All the ice around us has long-since broken up or been ground into fragments. But our MOSAiC floe, selected for the expedition back in October 2019, continues to offer an impressively stable basis for our work. Nevertheless, even this floe will soon end its lifecycle in the marginal ice zone. Today we measured a balmy 14 degrees Celsius 300 m above the floe, and the melting is in full swing. For the last phase of MOSAiC, our focus will be on the freezing phase: the last piece of the puzzle in our observations of the Arctic’s annual cycle. Accordingly, in the last phase we will proceed far to the north, where the freezing will soon begin.” This will most likely take place in mid-August, once the last resupply and exchange of research staff and crew have been completed.

Hopefully they are stocking up with more buoys  ;)
Yesterday's S1

Today's fomo image at least 3 is 4 weeks old

44
Arctic sea ice / Re: MOSAiC news
« on: July 27, 2020, 02:59:50 PM »
Sea Ice Ticker No. 46, 27 July 2020: Central Arctic much too warm for July
Quote
The Central Arctic is currently much warmer than the long-term mean, continuing the trend that has been apparent since June this year. Average air temperatures at the 925 mb level (roughly 760 m above sea level) for the first half of July were unusually high over the central Arctic Ocean – up to 10 degrees Celsius. These above-average temperatures were connected to high sea-level pressure centred over the East Siberian and Chukchi Seas. Arctic temperatures along the Russian coast were near or slightly above average. This represents a significant change from June, when temperatures along the Siberian coast of the eastern Laptev Sea were up to 8 degrees Celsius above average. It is likely that these high temperatures, combined with ice movement away from the coast, initiated early ice retreat along the Russian coast, and the opening of the North-East Passage. At present, the ice extent is extremely low – the lowest level for this time of year since the beginning of satellite observation. Sea-ice extent in the Arctic has been at a historically low level since 1 July 2020. On 19 July, the ice extent was 570,000 km² lower than the former record low in 2019. This sea-ice loss is represents an area roughly the size of France. 26 July this difference reaches still a value of circa 260.000 km². The coming weeks will show how this will affect the overall ice development and the MOSAiC expedition.

This ani shows all the mosaic buoys that I could find to see how they coped. One is temporarily spinning in the eddy, another has possibly met it's end. No drift speed.

45
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 11:30:22 PM »
amsr2-uhh, atlantic side, jul1-25

46
Arctic sea ice / Re: What the Buoys are telling
« on: July 26, 2020, 09:51:42 PM »
Added a few more buoys to the drift animation. Someone is collecting a large swath of data in the Beaufort/Chukchi

47
Arctic sea ice / Re: MOSAiC news
« on: July 26, 2020, 02:38:00 PM »
Added couple of drifter buoys in the Greenland sea (not on ice) for a wider perspective

48
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 10:21:09 PM »
What is the likelihood that the entire ice sheet will unfasten from the CAA and Greenland?
Quite likely for a few days.

Drift update from a few more iabp buoys, including one in the ESS and a few more mosaic buoys on the atlantic side. Also one that's apparently being deployed in the west spitsbergen current.
click 10MB

The second animation is shorter with 10s delay in case anyone needs the numbers.
The titles are incorrect. These are not all whoi buoys, just iabp
edit: lol bbr. How will it hit an iceberg if they all melted?   ;)

49
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 06:04:20 PM »
I believe this more of a coincidence than meets the eye. In normal years the deep Beaufort is much emptier of ice, the shallower ESS often has lots of ice at this stage. And this year the deep Laptev/CAB sector is ice-free.
amsr2-uhh overlaid onto gmrt bathymetry, minimum jaxa dates, 2012-2018
must add 2019 sometime.
edit:Perhaps someone will put together all the nsidc minimums one day. I think they go back a lot further. If they do, I will attempt to overlay them onto bathy.

50
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 02:34:22 PM »
whoi itp buoys, Beaufort, ocean temperature (and other data) at 6m depth.
click

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