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A-Team

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Re: MOSAiC news
« Reply #1150 on: September 13, 2020, 06:20:49 PM »
The bow radar has resumed! It seems that acquisition never stopped but perhaps transmission of files to shore has only now been possible.

This goes out 5km in all directions except towards off-ship experimental sites so is a bit hard to register with the recent drone overhead of Sept 6th which showed almost entirely experimental sites! They do not even have a phone cam strapped to the radar mast to time-lapse for a visible correlation. (This does not even require an app, they come capable.)

The first image below registers the drone with bow radar. FOMO does not share compass direction on the drone shot nor its time of day (often given ambiguously as 'ship time' rather than the UTC of the bow radar). The drone photo only goes out 3.3 multiples of ship length (~400m) and so has far greater resolution than the bow radar which goes out 5000 m but with only ~500 pixels for it.

At any rate, some incredible ice advection can be seen in the 6-hour frame rate of the mp4 below, as well as the usual opening/closing of leads. As the ice freezes, the bow radar shows more brittle fracture than the mushy scenes of quasi-independent floes from the Fram.

FOMO has not made clear whether power lines and fiber optic data lines are being run out to remote sensors (which are only 4-5 ship lengths away this time). Consequently it is hard to determine whether trails and lines have been disrupted by lead openings and floe shifts.

Fascinating though local ice motion may be visually, it is not at all clear how to describe it scientifically or compare year on year (ie is it fracturing more). After N-ICE2015, its (very different) bow radar was written up in highly obscure technical terms. The real goal is to correlate it with wind stress and mechanical strength of the ice so the latter tensor can be deduced over the whole pack (without a ship being there) since the wind and drag are known fairly well from reanalysis.

https://data.meereisportal.de/maps/animations/Iceradar/?C=M;O=A
« Last Edit: September 14, 2020, 12:57:50 AM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #1151 on: September 13, 2020, 10:54:08 PM »
Sub -12 C now:

  88.7  105.8 20-09-10 22:00      -12.4 
  88.7  106.0 20-09-10 21:00      -12.1 
  88.7  106.1 20-09-10 20:00      -12.6 
 

And then back to above 0C with freezing rain and 'diamond dust'

Niall Dollard

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Re: MOSAiC news
« Reply #1152 on: September 14, 2020, 01:05:54 AM »
Yes the colder air at surface has been replaced and the upper air is warm too over Polarstern. But not diamond dust. That's usually seen in almost near clear air with temperatures below -12 C. As the milder air moved in Polarstern was reporting snow grains at first but as temperatures rose near zero the grains were replaced with freezing rain.

Models are forecasting it to turn cooler again by Wednesday. But no doubt there will be many mild incursions too this autumn.   

A-Team

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Re: MOSAiC news
« Reply #1153 on: September 14, 2020, 02:07:09 AM »
In terms of correcting the full-time DWD meteorologist on board the Polarstern who entered that call on the hourly awiMet report going to ECMWF, not going to do that from where I sit in smokey Arizona.

The FOMO today seems to show an icebow flanking an air temperature inversion giving rise to a pronounced refracted solar mirage of a type commonly seen in the Arctic. The optics are discussed in the attached pdf.

Wayne, a member here who has lived many years in far north Nunavut, has written very extensively about these inversions and what they mean for conditions of the ice but on Neven's blog, not the forums.

But as you say, it's all going to change.
« Last Edit: September 14, 2020, 02:14:55 AM by A-Team »

Niall Dollard

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Re: MOSAiC news
« Reply #1154 on: September 14, 2020, 08:12:28 AM »
No. Not correcting the meteorologist on board PS but our esteemed forum member who mentioned diamond dust.The ww code reported by PS was 77, which is snow grains. (Diamond dust is code 76). Next reports then were freezing rain.

uniquorn

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Re: MOSAiC news
« Reply #1155 on: September 14, 2020, 11:33:22 AM »
Sorry about that. I mixed up the ww and the WW
I should have said snow or mixed rain and snow moving to with less significant rain
Quote
W1 -- Most significant weather in past 6 hours
W2 -- Less significant weather in past 6 hours

    0 -- cloud covering less than half of sky
    1 -- cloud covering more than half of sky during part of period and more than half during part of period
    2 -- cloud covering more than half of sky
    3 -- sandstorm, duststorm or blowing snow
    4 -- fog, or thick haze
    5 -- drizzle
    6 -- rain
    7 -- snow or mixed rain and snow
    8 -- showers
    9 -- thunderstorms
Quote
76 -- diamond dust

Recent weather is hovering around 0C with continuous light drizzle.
« Last Edit: September 14, 2020, 12:49:10 PM by uniquorn »

A-Team

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Re: MOSAiC news
« Reply #1156 on: September 14, 2020, 01:45:12 PM »
Somewhere up-forum, all the weather commentaries for the entire expedition was extracted into a flatfile database and a MS Word-type glossary system proposed to stub in the code lookups to eliminate tedious and error-prone code lookups. No one picked up that baton.

Meanwhile, the last three bow radar frames for the 13th show a very large lead opening immediately in front of the Polarstern's bow if not right under the ship. We have no better time resolution for the cycle of closed, open, closed than 12 hours but it may have been much shorter. The lead is 68m wide on average; 6 km of length is visible to the outer edge of the image. It is a rocker event, so more a pivot than a shear.

This may or may not have done any damage to gangways, ice anchors, cables and experimental set-ups. It's possible field work was ongoing despite the miserable weather and staff separated by open water from the ship. Radar coverage of the experimental area has been blocked out the entire trip whereas N-ICE2015 had full 360º coverage.

All we know for certain at this time is that 'Follow Mosaic' will downplay -- or not even mention -- the incident no matter how much damage it caused. Indeed the 13th on FOMO is all smiles on a nitrate survey on yet another idyllic day.

The ship is in a surprisingly active area of ice motion due to a small cyclone enveloping it so this event will not be the end of it.
« Last Edit: September 14, 2020, 04:24:56 PM by A-Team »

FishOutofWater

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Re: MOSAiC news
« Reply #1157 on: September 14, 2020, 02:57:08 PM »
As the light goes away and the inversions over the ice intensify the ice edge becomes like a stationary front between air masses because the water still has heat. The pole is shockingly close to the ice edge this September so storms will be intensified by the boundary and can be expected to cause the Mosaic team many challenges.

The large scale synoptic pattern has chains of storms tracking from the north Atlantic into the subpolar seas and into the Arctic ocean proper. The record high heat content of the north Atlantic and possibly the Atlantic side of the Arctic ocean is contributing to the storminess. We won't hear about the impacts of these storms from the PR person, but expect more of them. The effects of the loss of sea ice on the Atlantic side of the Arctic ocean are affecting CFS model forecasts of the location of the polar vortex this fall, causing it to move towards the north Atlantic in the model. If this verifies, storminess will be intensified in the Barents and Kara seas as winter sets in.

I would guess that graupel was falling before it turned to freezing rain. Graupel is icy snow, a tiny ice ball with a core of snow.

uniquorn

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Re: MOSAiC news
« Reply #1158 on: September 14, 2020, 03:46:39 PM »
Quote
Somewhere up-forum, all the weather commentaries for the entire expedition was extracted into a flatfile database and a MS Word-type glossary system proposed to stub in the code lookups to eliminate tedious and error-prone code lookups. No one picked up that baton.

63 downloads, quite popular. Though no further analysis from them.
Looking at some thread stats is valid as we near the end of the mosaic project. Gauging popularity of areas of analysis can be useful to determine viewer interest and whether sizing an animation to fit the forum's tight limits is worth the effort

Thanks, I hadn't  heard of diamond dust or graupel before.

A-Team

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Re: MOSAiC news
« Reply #1159 on: September 14, 2020, 05:10:17 PM »
Quote
FooW: consider the big picture
This is helpful. We are taken up documenting day to day noise but it is all happening for underlying climate change reasons.

The composite below looks at the position of the Polarstern relative to the North Pole, the AMSR2 pole hole of no data, the wind power density, the distance to the ice edge, and a cyclonic storm barreling up from the North Atlantic that has brought measurable precipitation (2nd image, 3hr accumulation).

The ship has been drifting rapidly and may reach the pole yet though the ice we wanted them to look at will have drifted away. They are currently 454 km away from the ice edge based on the pixel ratio for the pole to Morris Jesup. Note a strong wind is bearing down on a vulnerable region of ice north of SevZem which could still dramatically lower its concentration.

Both images benefit from a click. You are wasting your time on this forum if not looking beyond thumbnails. We cannot accurately downscale indexed color.
« Last Edit: September 14, 2020, 05:35:29 PM by A-Team »

A-Team

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Re: MOSAiC news
« Reply #1160 on: September 15, 2020, 03:57:16 PM »
The worst ice movement of the whole year-long expedition is happening. It is probably not a risk to the ship itself (though the rudder got rammed by a floe earlier) but puts experimental equipment out on the ice in jeopardy.

'Follow Mosaic' has not said if they can keep field work going safely under these conditions; in the past, great effort went into just keeping power lines out and sensors upright and running. Today's post is all about chlorophyll, fading light and zooplankton. The photo could be a week old for all we know.

It's hard to see the scientific value of sampling a hole or two over winter in an immense ocean; how long will biological data stay relevant in the fast-changing Arctic. Does AWI believe the coming BOE will bring a fisheries and fossil fuel bonanza?

https://www.meereisportal.de/en/mosaic/sea-ice-ticker/ #53  diatom Melosira arctica
https://www.tandfonline.com/doi/abs/10.1080/0269249X.2013.877085
« Last Edit: September 16, 2020, 02:13:59 PM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #1161 on: September 15, 2020, 07:54:21 PM »
drift speed increased during sep13-14. click for motion

uniquorn

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Re: MOSAiC news
« Reply #1162 on: September 15, 2020, 09:32:47 PM »
That 25km2 of bow radar might overlay nicely onto buoy drift now that it is relatively static. A shame it's not hourly.
This is a wider view of the previous animation here with the tight cluster at the centre.

intermittent light snow


  Lat  Long  YY-MM-DD  UTC     Wind       T(C)  N  h  VV  wwWW  ICE  Pnn(hPa)
  89.1  108.3 20-09-15 20:00    4  230     -4.6  /  /  //  //// ///// 1005.2
  89.1  108.1 20-09-15 19:00    5  210     -4.9  /  /  //  //// ///// 1005.2
  89.1  107.9 20-09-15 18:00    5  200     -4.7  /  /  //  //// ///// 1004.9
  89.1  107.6 20-09-15 17:00    4  220     -4.7  /  /  //  //// ///// 1004.8
  89.1  107.3 20-09-15 16:00    4  230     -4.9  /  /  //  //// ///// 1004.8
  89.1  107.1 20-09-15 15:00    4  200     -4.9  8  2  98  7082 49/9/ 1004.7
« Last Edit: September 16, 2020, 11:26:40 AM by uniquorn »

A-Team

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Re: MOSAiC news
« Reply #1163 on: September 16, 2020, 02:55:26 PM »
The frenetic motion of floes continued for another day on Sept 15th. The bouncing floe within the open lead is 170x170m; the scale is 10m per pixel. Impacts on Mosaic operations remain undisclosed.

The Polarstern is represented by the gray ball; it is moored with its starboard bow against the ice (not shown as blocked from radar), so the bow is pointing east in the time series and ice motion below the ship is black (not visualized). The frames are 0.1 sec apart vs 6 hours apart on board so the motion is sped up 6*60*60*10 = 216,000 times, a lot but less than commonly done for Jakobshavn or Petermann glaciers.

The last frame is midnight on Sept 15th. The floe is at 89.1º latitude with air temperatures -4º, low enough to put a much-fractured ice skim on opening/closing leads. They do have kayaks on board but helicopter, fog permitting, is the main way to reach stranded equipment if indeed their specific floe is affected.

The winds at the ship have died down considerably from their peak of 16m/s but wind stress nearby can still propagate ice motion to their site.

The avi's frame of reference, while basically co-moving (lagrangian), has never been explained. The radar antenna rotates in a full circle, taking less than a minute to capture its scene. Of the 360 scenes taken per six hours, only one is retained for the shared video. The rest are shown on the bridge and also on meeting room monitors.

The bridge also has an instrument that measures ship heading, the angle between the mid-ship half-axial line and a line to north pole. (The magnetic pole cannot be used in the high Arctic.) This heading is shared to the radar display along with other parameters that have all been cropped out, with truncated 2dp lat lon and timestamp restored.

In production, each frame is rotated as specified by ship heading so north is always straight up the white scale bar. The ship is rigidly attached on its starboard side its floe by six sea anchors except when it breaks loose; anchors are checked and re-sunk daily as necessary.

The floe commonly rotates during the six hour gap between frames. This causes the 83º black-out area to rotate after correction to the fixed north pole heading. Recent months have seen a red ball added to each image to indicate the ship, rather than a more logical icon that shows bow and stern.

The center of the radar image (which verifies as a true circle) lies near the bottom of this red ball, NOT on its center. This is the location of the bridge mast on which the rotating radar is mounted several dozen meters above the water.

We do not know if the black-out area is symmetric with respect to the ship's long axis (perhaps because of intervening metal masts or smokestack); it may not extend to the experimental area to avoid rfi. If so, ice immediately port side is shown. The comparable radar on N-ICE2015 showed 360º.

The clumsy north icon obscuring the data is a recent add-on that serves no known purpose. It walks east and west without holding its lat lon, its position seemingly in accordance with blackout zone rotation.

Because the ship is so close to the pole, latitude lines converge rapidly. Only the white bar center goes straight up. Other latitude lines are straight but angled appropriately. The longitude lines are convex up and likely the expected arcs of circles.

The floe is mostly drifting along with the regional ice pack (which is known compact, ie at 100% sea ice concentration at 3x3 km resolution) but sometimes cohesive motion breaks down and floes in the scene have quasi-independent motions compatible with each other's constraints.

Motion of the Polarstern can be marked up within the video by tracking a lat lon intersection between frames. This gives jointed line segments and segmental mean velocities at six hour intervals. However GPS on ship and adjacent buoys are half-hourly or less with 4 dp precision, meaning a spreadsheet with a haversine column shows ship rotations and translations much better. as seen in uniq's many buoy products.

The speeds are rather high relative to those seen during the past year, over 1.2 km/hr for extended stretches. The Polarstern was subjected to a CCW gale force wind (small cyclone) during the affected period, likely responsible for the stress leading to the dramatic ice break-up motions.

The red bars on the buoy speed graphs show that six-hour sampling is not close enough to capture ups and downs in floe speeds whereas the half-hour buoy iridium call are satisfactory.

The buoy data is at the meereis gallery; the excel-ready haversine formula needs lat lon data in the first two columns; the csv speed file is attached.

=ACOS(COS(RADIANS(90-A2)) * COS(RADIANS(90-A3)) + SIN(RADIANS(90-A2)) *SIN(RADIANS(90-A3)) *COS(RADIANS(B2-B3))) *6356.752

https://tinyurl.com/yx9yle3o

uniquorn

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Re: MOSAiC news
« Reply #1164 on: September 16, 2020, 09:36:21 PM »
Probably best with VR headset but you can use the mouse (or finger) to look around. Look up first to  lose the auditorium.


uniquorn

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Re: MOSAiC news
« Reply #1165 on: September 16, 2020, 10:05:08 PM »
A lot of good videos on https://twitter.com/seaice_de

Quote
The Polarstern is represented by the gray ball; it is moored with its starboard bow against the ice
Quote
Lars Kaleschke@seaice_de
12 Sep  Too much tension? Be careful with the anchor line. A very dangerous environment. @MOSAiCArctic  - April 28



A-Team

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Re: MOSAiC news
« Reply #1166 on: September 18, 2020, 11:37:28 AM »
Floe motion is as crazy as ever around the Polarstern's position of 89.1  107.4 despite mild winds of 4m/s and cold temperatures of -9.4ºC. Despite two weeks of increasing ice chaos documented on bow radar, there has been no mention to date of its effects on scientific equipment deployment on Follow  :) :) :) Mosaic.

Instead, various science for science sake studies on snow flakes and algae are described that seem like escapism. Thee could just as well have been done in the Baltic. It might have been better to have just concentrated on studies relevant to climate change. There's been almost no mention of that over the last year.

The six hour time series raises questions about whether distinct floes exist at this near-pole site. What's seen are blocks of ice joining up with other blocks of ice, then leaving for another. When that repeats, the block boundaries are often different with new fractures and leads as boundaries. Spatial constraints limit the options though so despite many breaks and rejoins the picture can eventual return to resemble to the start.

The notion of solid SYI ice blocks welded together into a matrix with weak intervening FYI freezes doesn't seem applicable. Without having the whole history of formation, how are floe boundaries defined if most are ever-changing composites?
« Last Edit: September 18, 2020, 12:00:32 PM by A-Team »

OffTheGrid

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Re: MOSAiC news
« Reply #1167 on: September 18, 2020, 08:37:02 PM »
Watch out Mosaic!

There's been 14 second swells of 0.2 m coming out on the ESAS, AFTER passing all the way from Fram, under them <reader beware, this is nonsense>. May be having the effect you point out on the floe motion ATeam.
Also outburst flushing from Greenland, which looks to be going through exponential runaway geothermal blowout <reader beware, nonsense>, has been launching submarine landslides that are shedding violent fresh upwellings, and possibly mini tsunami surges, which could look like standard tidal effects, since the subglacial outbursts occur primarily at high tides. <nonsense>
Their "pretty frost flowers" are sadly a symptom of large energy injection from water vapour condensing. Driving bottom melt.
Gotta click the stupid gif to see the 11m long period waves heading for them in a few days.

<Warnings added. Posts must be fact-based. O>
« Last Edit: Today at 06:39:14 PM by oren »

binntho

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Re: MOSAiC news
« Reply #1168 on: Today at 05:34:05 AM »
Also outburst flushing from Greenland, which looks to be going through exponential runaway geothermal blowout, has been launching submarine landslides that are shedding violent fresh upwellings ... and possibly mini tsunami surges, which could look like standard tidal effects, since the subglacial outbursts occur primarily at high tides.

What are you smoking?
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nanning

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Re: MOSAiC news
« Reply #1169 on: Today at 12:00:28 PM »
Makes mostly sense to me,  a different style of writing, but then.. I am a smoker :)
I have been thinking about submarine landslides. Also to try to understand the north-east Greenland strangeness.
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A-Team

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Re: MOSAiC news
« Reply #1170 on: Today at 01:57:09 PM »
The Mosaic expedition seems to be winding down/falling apart despite being scheduled to continue until Oct 12th. That's not unusual, the horse begins to gallop when it smells the barn.

It hasn't been made clear whether the 12th is the date when field equipment is borught in and the engines fired up or the date of arrival at the dock in Tromsø. The ice has been thickening but not to point where the return passage of a week would be hindered.

The ship's position is currently 89.1  110.7, quite close to the pole but some 2274km from port at 69.6 18.9 which would require about 100 hours of travel time in calm seas.

Ice movement yesterday continued to be extreme, or rather no one seemed to have suspected prior to the expedition what the new normal would be. The long lead re-opened again; it extends off the edge of the radar so 5km or more. The pack also has a bulk rotational component and that 179m broken-off floe pounding on the port side of the ship. This is surprising since the winds at their position have been brisk but not exceptional, below 10m/s.

uniquorn

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Re: MOSAiC news
« Reply #1171 on: Today at 03:35:13 PM »
drift update from P176.
2 submarine landslides a day seems unlikely. I think I'll stick with tides.
« Last Edit: Today at 03:52:43 PM by uniquorn »

gandul

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Re: MOSAiC news
« Reply #1172 on: Today at 04:01:39 PM »
Interesting gifs, now I understand offthegrid a bit better.

binntho

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Re: MOSAiC news
« Reply #1173 on: Today at 04:09:06 PM »
Makes mostly sense to me,  a different style of writing, but then.. I am a smoker :)
I have been thinking about submarine landslides. Also to try to understand the north-east Greenland strangeness.

So "exponential runaway geothermal blowout" makes sense to you? OTG entire line of reasoning is from never-never land and does not apply to planet Earth. EDIT: In fact it's so totally off the grid that I suspect OTG is a nom-de-plume of someone making fun of us by threading pseudoscientific waffles on his hook and seeing how many bites he gets.
« Last Edit: Today at 04:38:21 PM by binntho »
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binntho

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Re: MOSAiC news
« Reply #1174 on: Today at 04:14:32 PM »
drift update from P176.
2 submarine landslides a day seems unlikely. I think I'll stick with tides.
Absolutely (grrmble grrmble) and the gif is fantastic, almost like a Micky Mouse picture. But as usual I miss scale from your gifs, and it is tedious to have to freeze two frames, read the coordinates and then calculate the distance to see that your gif is appr. 10 x 5 km square.

EDIT: The speed of drift swings between 10% and 20% of normal walking speed. And the tidal swings are only a few hundred meters each way. The circular movement I guess has more to do with changing wind direction than anything else.
« Last Edit: Today at 04:23:40 PM by binntho »
because a thing is eloquently expressed it should not be taken to be as necessarily true
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uniquorn

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Re: MOSAiC news
« Reply #1175 on: Today at 04:22:04 PM »
The default scale is utm km which may be reasonably accurate this close to the pole, though confusing to some, so I normally remove it. Recent location of most of the nearest buoys to PS

uniquorn

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Re: MOSAiC news
« Reply #1176 on: Today at 05:53:55 PM »

EDIT: The speed of drift swings between 10% and 20% of normal walking speed. And the tidal swings are only a few hundred meters each way. The circular movement I guess has more to do with changing wind direction than anything else.

Great. As you guessed that one hopefully you will run the numbers to prove it. Hourly wind direction from PS is here   P169 is near if you need buoy data.
I suspect it is the combination of both since wind drift appears to be of the same order of magnitude as 'tidal drift' and it's a more likely explanation than continuous tight wind vortexes at multiples of walking speed. 

Here attempting to overlay the tight group of buoys onto bow radar. Maybe they are either side of a fault line or along a ridge. click for animation.
« Last Edit: Today at 08:57:07 PM by uniquorn »

oren

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Re: MOSAiC news
« Reply #1177 on: Today at 06:40:19 PM »
OTG, I will delete further fantasy nonsense posts, be warned.