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uniquorn

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Re: MOSAiC news
« Reply #200 on: November 03, 2019, 09:58:30 PM »
A longer timescale view of the mosaic buoy network building up, day275-307 (today), no projection.
Dropouts (buoy fails to report or report is not recorded) show clearly using delaunay.  A large number of buoys close to PS dropped out on day304.
« Last Edit: November 03, 2019, 10:58:40 PM by uniquorn »

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Re: MOSAiC news
« Reply #201 on: November 04, 2019, 03:42:15 AM »
Incredible floating effect! The Polarstern buoy array is such a neat idea for extending outwards from the intensively studied Mosaic floe, too bad they hardly ever work for more than a couple weeks. Maybe just stick an iphone inside instead of all that no-good custom electronics?

Below is ice thickness according to the laser altimeter and soil moisture radar ice thinness ... the palette is monotonically proportional to ice thickness (though not linearly) so it displays more or less correctly in bump map view. Because the .nc file is provided, the data can be redisplayed in polar stereographic with one of the carefully designed linear palettes available in Panoply.

However, it appears that the Cryo2Smos project has died or gone into hibernation. Its daily archive has not been updated since the week ending Oct 30th. Only nine days of product were ever produced. Meanwhile, U Bremen continues to update smos-smap and smos alone even though these were supposedly taken away by U Hamburg/AWI.

Index of /sea_ice/product/cryosat2_smos/v202/nh/LATEST/
https://seaice.uni-bremen.de/data/smos_smap/png/north/2019/
https://seaice.uni-bremen.de/data/smos/png/20191103_hvnorth_rfi_l1c.png

The surface plot (needs click) bears an uncanny resemblance to grayscale values on plain vanilla Ascat, especially that extended pocket of thick white (low salinity) mature MYI ice around the pole that has been there consistently on Ascat for many many months.

It's not quite clear why the ice above the CAA is thiner (as historically that has been the very thickest) but that is seen in multiple ice thickness products. The Polarstern (white star) is currently situated in fairly thin ice, surprisingly with thicker ice shown farther south on flanking meridians.

The ship has been moving rapidly east due to a persistent clockwise rotation of the ice pack (as seen on OsiSaf: red star within green cruise bounding wedgie). If this keeps up (it won't), the Polarstern would be home for christmas. The cruise history to date:

Lat  Lon  Day   Hour  Wind(m/s) Wind (dir)
85.9 119.7 04 11 19   12:00    9 80
85.9 119.8 04 11 19   11:00    8 80
85.9 119.9 04 11 19   10:00    8 90
85.9 119.9 04 11 19   09:00    9 90
85.9 120.0 04 11 19   08:00    9 90
85.9 120.1 04 11 19   07:00    8 90
85.9 120.1 04 11 19   06:00    8 90
85.9 120.2 04 11 19   05:00    8 90
85.9 120.2 04 11 19   04:00    9 90
85.9 120.3 04 11 19   03:00    9 90
85.9 120.4 04 11 19   02:00    9 80
85.9 120.5 04 11 19   00:00    9 90
85.9 120.6 03 11 19   23:00    9 90
85.9 120.6 03 11 19   22:00    8 90
85.9 120.7 03 11 19   21:00    9 90
85.9 120.8 03 11 19   20:00   9 100
85.9 122.2 02 11 19   20:00   5 120
85.8 122.7 01 11 19   20:00   4 160
85.8 123.2 31 10 19   20:00   5 120
85.7 124.0 30 10 19   20:00   7 100
85.7 124.9 29 10 19   20:00   7  90
85.6 125.9 28 10 19   20:00   8 100
85.5 126.7 27 10 19   20:00   7 110
85.5 127.2 26 10 19   20:00   6 120
85.5 127.7 25 10 19   20:00   4  90
85.4 128.5 24 10 19   20:00   8  90
85.4 129.6 23 10 19   20:00   4 100
85.3 130.7 22 10 19   20:00   10 100
85.2 132.2 21 10 19   20:00   12 110
85.0 132.8 20 10 19   20:00   9 190
84.9 133.2 18 10 19   20:00   11 170
84.8 133.0 17 10 19   20:00   2 220
84.8 133.3 16 10 19   20:00   5  40
84.8 134.1 15 10 19   20:00   6  50
84.8 134.4 14 10 19   20:00   4 330
84.8 134.8 13 10 19   20:00   8 340
84.9 135.4 12 10 19   20:00   4  50
84.8 135.8 11 10 19   20:00   4 290
84.9 135.3 10 10 19   20:00   6 290
84.9 135.9 09 10 19   20:00   4  80
84.9 136.2 08 10 19   20:00   6 350
85.0 135.1 07 10 19   20:00   13 270
85.1 134.0 06 10 19   20:00   5 280
85.1 133.8 05 10 19   20:00   4 270
85.1 134.1 04 10 19   20:00   7 70
« Last Edit: November 04, 2019, 03:07:24 PM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #202 on: November 04, 2019, 09:20:04 PM »
A closer look at whoi itp102
Quote
ITP102 was deployed on a 0.7 m thick ice floe in the Transpolar Drift on October 10, 2019 at 85° 7.9 N, 135° 34.1 E in collaboration with the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from the Russian Research Vessel Federov. On the same icefloe, a Naval Postgraduate School Arctic Ocean Flux Buoy (AOFB) and Seasonal ice mass balance buoy were also installed. The ITP includes a second generation prototype MAVS current sensor operating on a pattern profiling schedule including 2 one-way profiles between 7 and 760 m depth each day and SBE-37 microcat fixed at 6 m depth.
The profile contours show small changes down to 50m since the start and the microcat highlights temperature and salinity changes at 6m depth since day300. Here we are also using macid's 3d R analysis to focus on temperature down to 50m showing a small rise of up to 0.16C at ~30m.

A rise in temperature and drop in salinity  at shallow depth could imply some bottom melt but no doubt there are other reasons for these conditions in this area.

A-Team

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Re: MOSAiC news
« Reply #203 on: November 05, 2019, 10:48:17 AM »
No question, where the Polarstern originally moored was very dicey given thin weak ice and strong winds (which have since dissipated). Temperatures have been quite low but the thickening process is fairly slow.

The animation below follows this development on cryo2smos which is presumably the best of both worlds in terms of satellite thickness determination. These files are produced somewhat irregularly and require a week of Cryo2 data along with daily Smos. The latter nine frames of the animation represent the Nov 2nd differenced with the early ones back to Oct 22nd.

The Polarstern is currently at 85.9N 118.7E with winds at 32 km/hr from 50º with a temperature of -23.1ºC at 07:00 UTC on 19-11-05. The clockwise rotation of the ice pack has continued another day, resulting in more easterly longitude while staying at the same distance from the pole.

Mosaic will not be sharing their ice thickness measurements any time soon so we need to follow nearby buoys with the appropriate ice profiling instruments. At some point, a 3DxT model will be produced of the 2.3 x3.5 km floe ice and snow thickness with the help of the underwater ROV with upward looking sonar and helicopter-borne downward laser scanning.

The three Sentinel-1B images at 02:22, 04:00, and 05:38 UTC this morning have sufficient resolution to show significant motion of the Polarstern and the Mosaic ice camp. The main image uses an earth-stationary coordinate system and the inset one ship-stationary.

On the whole, the local ice pack is moving uniformly en bloc but some non-threatening ice dynamics can be seen within the floe itself, though that may be partly attributable to jumbled ice reflecting satellite beams with slightly different orbits at slightly different efficiencies.
 
The Polarstern has appeared in 49 S1AB images since mooring to the floe (through Nov 5th). The only omissions are Oct 9th and 31st. That offers many opportunities to control variables, such as limiting analysis to images from a particular orbit on a particular time on a particular instrument.

The 7th Mosaic-launched buoy officially died today, namely 300234068713430 CapO CTD AWI.
« Last Edit: November 06, 2019, 02:55:46 AM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #204 on: November 05, 2019, 03:08:25 PM »
Quote
the thickening process is fairly slow
three of the mosaic mass balance buoys at https://www.cryosphereinnovation.com/382860 indicating 30- 6073cm thickness, though that appears to include snow.
Quote
The 7th Mosaic-launched buoy officially died today, namely 300234068713430 CapO CTD AWI
Two Obuoys appear to have failed at roughly the same time, though quite different locations. The pressure data for --519770 suggesting a trauma of some kind on the19th oct. Click to run the animation of Obuoy charts provided by meereisportal.de

Following up on the small temp/salinity changes shown by itp102 above. Here are the obouys salinity at 20m depth (--169760 10m sensor has failed). Obuoy data is collected every 10minutes, the files are around 4000 lines long today. The animation has 500 frames but is still quite small, showing a pleasing amount of detail. Red dot is PS position yesterday based on https://follow.mosaic-expedition.org/ diary.
« Last Edit: November 05, 2019, 03:30:23 PM by uniquorn »

blumenkraft

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Re: MOSAiC news
« Reply #205 on: November 05, 2019, 04:32:44 PM »
There is a podcast by MOSAiC Leader Markus Rex. In German language though.

Link >> https://www.mosaic-expedition.org/arctic-drift-das-audiologbuch/
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Re: MOSAiC news
« Reply #206 on: November 05, 2019, 08:55:15 PM »
Quote
podcast by MOSAiC Leader Markus Rex. In German language though.
I clicked all over that page, couldn't get it to play. Is it same pre-trip interview he gave whose transcript is online?

Finally an interesting photo!

First, note the new hawsers off the bow to the ice anchors mentioned earlier. The triple is taut but the double pair in front is slack, suggesting slight ice motion. If you set some lines slack and others taut, the wind will rip your vessel loose successively.

The snow is not ankle deep, as befits the Arctic Ocean as a drier desert than the Sahara. It looks very powdery though and thus is not entirely negligible as insulation. Classical R values given in earlier post aren't the whole story because the wind, eddies and turbulent air flow can't reach the ice to take heat away. Snow flurries can be seen in the searchlight beam.

The freeboard can perhaps be estimated from the shovel blades. Note the ice already trying to grow in from the sides. The big blocks, drilled around their periphery and lifted out by the ship crane look to somewhat over a meter. The photo is on the starboard side so thus this is Fortress ice, not flanking fragile melt pond.  The hole is not locatable on the lidar altimeter map but it doesn't matter since no scale was provided for that.

Some of factoids are puzzling. Are liquid volumes normally given in tonnes? Is the Polarstern using filthy bunker fuel or something higher grade, given all the wx towers and measurements. Helicopter fuel, that has to be separate. In Greenland, that is brought in in bladders left on the ice, not pumped into the hold.

Mosaic has absolutely no idea if they will ever get any closer to the North Pole than they are now, much less if they will be within 200 km (>88ºN) for 60-90 days. Modeling of drift is completely delusional -- it amounts to a seasonal weather forecast 350 days out and a whole lot more.

Each year now is effectively one-off; under rapid Arctic change it is statistically fallacious to think 12 years of unweighted previous drifts is somehow random sampling from an underlying population whose properties can be deduced and from which reliable inferences can be drawn. The Polarstern should steer clear of the shoals of model pseudoscience.

Quote
"All models are wrong but some are useful."
Yes, but how do we know in advance which ones are useful and which ones are horribly misleading, dangerous, or even worse than wrong?
« Last Edit: November 06, 2019, 03:49:37 AM by A-Team »

blumenkraft

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Re: MOSAiC news
« Reply #207 on: November 05, 2019, 10:13:23 PM »
Here are links to a podcast player where you can listen directly and comfortably, A-Team.

Folge 1 - vor der Abfahrt
Link >> https://overcast.fm/+UIoJphYxM

Folge 2 - Polarlichter, Bar-Abende und die Suche nach der geeigneten Scholle
Link >> https://overcast.fm/+UIoJQ6ETQ

Folge 3 - Die richtige Eisscholle
Link >> https://overcast.fm/+UIoJYhHbg

Folge 4 - Eiscamp, Polarnacht und Abschied von “Akademik Fedorov”
Link >> https://overcast.fm/+UIoKtDYcU
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uniquorn

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Re: MOSAiC news
« Reply #208 on: November 05, 2019, 10:40:15 PM »
A-Team's calculation of 346km from Polarstern to the pole caused me to question the automatic lat/lon kilometer axes on some of the buoy animations above. They are based on a conversion of lat/lon to utm coordinates for the PlotSvalbard mapping package. Many thanks to

   Mikko Vihtakari (2019). PlotSvalbard: PlotSvalbard - Plot
   research data from Svalbard on maps. R package version 0.8.5.
   https://github.com/MikkoVihtakari/PlotSvalbard

for an excellent resource.

https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system
Quote
The Universal Transverse Mercator (UTM) is a system for assigning coordinates to locations on the surface of the Earth. Like the traditional method of latitude and longitude, it is a horizontal position representation, which means it ignores altitude and treats the earth as a perfect ellipsoid. However, it differs from global latitude/longitude in that it divides earth into 60 zones and projects each to the plane as a basis for its coordinates. Specifying a location means specifying the zone and the x, y coordinate in that plane. The projection from spheroid to a UTM zone is some parameterization of the transverse Mercator projection. The parameters vary by nation or region or mapping system.

Most zones in UTM span 6 degrees of longitude, and each has a designated central meridian. The scale factor at the central meridian is specified to be 0.9996 of true scale for most UTM systems in use.

The image below from the PlotSvalbard documentation shows how the UTM distance relates to the panarctic map used in the buoy animations based on the macid code. I'll crop them off in future as they may be misleading.

uniquorn

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Re: MOSAiC news
« Reply #209 on: November 05, 2019, 11:26:57 PM »
Here we are showing the mosaic Sbuoys which measure snow-ice distance. The first animation (click to run) shows the charts kindly provided by meereisportal which appear to show 9 buoys with sensor1<20cm and one at over 1m.
What little I know about snow buoys comes from here
https://forum.arctic-sea-ice.net/index.php/topic,2906.msg233006.html#msg233006
Quote
These seem to work by taking four sonar measurements from above, with calibration of actual snow at time of deployment. The sonar footprint is about 10 sq meters ... necessary because the snow pack is quite variable and subject to drift accumulations (or bare ice spots).

Maybe --083129 is in a hole or close to a ridge.
The second animation showing only sensor1 and drift.


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Re: MOSAiC news
« Reply #210 on: November 06, 2019, 01:41:32 PM »

Some of factoids are puzzling. Are liquid volumes normally given in tonnes? Is the Polarstern using filthy bunker fuel or something higher grade, given all the wx towers and measurements. Helicopter fuel, that has to be separate. In Greenland, that is brought in in bladders left on the ice, not pumped into the hold.


When talking about fuel it's not unusual to talk about tonnes particularly for ships, in this case Polarstern has 4 large Diesel engines, I doubt that they will be using all of them and possibly only one for power on board,  More info at the link.
https://www.awi.de/en/expedition/ships/polarstern/the-symbol-of-german-polar-research.html

Oh and here's a picture of them.

blumenkraft

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Re: MOSAiC news
« Reply #211 on: November 06, 2019, 05:17:14 PM »
Holy son of a moly what an awesome picture. 😍
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Re: MOSAiC news
« Reply #212 on: November 06, 2019, 05:25:02 PM »
Quote
here are links to somewhat dated podcasts by Mosaic co-leader Markus Rex
Very helpful, thx!
Quote
Only one engine burning bunker fuel for electric power while frozen-in
Would Greta Thunberg would accept a ride back to Spain on a ship that burned high sulfur MDO for a year in the pristine Arctic? Oily rag left on engine room floor --> spontaneous combustion --> sterkt forbudt i Tyskland på skip --> hopefully stowed before leaving Tromsø.
Quote
What is IMO 2020? The International Maritime Organisation (IMO) has ruled that from 1 January 2020, marine sector emissions in international waters be slashed. The marine sector will have to reduce sulphur emissions by over 80% by switching to lower sulphur fuels.
Not seeing anything in the planning documents that indicates Mosaic intends to comply. They don't think the Polarstern will be reachable even by icebreaker during midwinter leg 2.

This morning, the Polarstern drifted 74 pixels east and 4 north or 73.1 pixels at WGS84 41 meter per pixel resolution on a pair of S1B's orbitally angled at 49º and separated by 3.27 hours in timestamp with no indication of significant shifting ice (final interferometric frame of lagrangian animation). This pencils out to a speed of 22 km/day.

This measure of drift fits with the multi-day cw rotating icepack depicted by OsiSaf today. Indeed, observed ice motion has finally become the classic Beaufort arm coastal extension (not gyre) with furnished by ice above the CAA, chaos in the ESAS/Laptev/Kara, constrained circumpolar drift (not trans) centered on the Pole, with export out the Fram and SV-FJL gap.

The Polarstern is currently located at 85.9º,117.4º at 14:00 UTC which is 1298 vincenty km from the flux gate at the entrance to the Fram Strait where the voyage is meant to end after 350 days. Per google earth, again in WGS84 ellipsoid geodesics, if the current velocity of ice drift keeps up (it won't), the Polarstern will reach its destination in 59 days or on 04 Jan 2020.

(Humor alert: this simple-minded estimate is just to poke fun at Mosaic's convoluted probabilistic drift route and arrival model.
« Last Edit: November 06, 2019, 06:27:40 PM by A-Team »

blumenkraft

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Re: MOSAiC news
« Reply #213 on: November 06, 2019, 05:29:29 PM »
Very helpful, thx!

Most welcome, sir. :)

Quote
the Polarstern will reach its destination in 59 days

That would be a bummer indeed.  :-\

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öliger Lappen auf Maschinenraumboden

Pah, scientists...
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Re: MOSAiC news
« Reply #214 on: November 06, 2019, 06:06:22 PM »
Somehow relevant.

What to Do if you see a Polar Bear

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Re: MOSAiC news
« Reply #215 on: November 06, 2019, 06:43:37 PM »
That risk recedes but does not go to zero as the distance from the Polarstern to the ice edge and open leads rapidly increases. Their staged response involves flares, blasts from the ship's horn, remote guard stations, night vision goggles, trip wires, bear prints in snow, shotguns for scientists, mausers for on-duty guards and so on. The polar bears though are accomplished ambush predators that can, like grizzly bears, outrun a wolf and tear open flimsy shelters. So it is a tough call for the bridge either way, especially with multiple isolated groups responding to a tripwire flare.

Some scientific Arctic expeditions also require a rescue swimmer to accompany people walking away from the ship. It is not possible to self-rescue once bulky clothes are wet and the timeframe is very short. The guard rope around the big CTD hole (above) is unsatisfactory but then it is well-lit so close to the ship. Otherwise, they have safe walking routes established and flagged.

Ridges and leads can form very suddenly but the effect is mostly stranding. Falling through melt pond drains or thinning ice is an issue more for late spring. It's never fully safe but then a motorway is even less safe.

I have not seen mention of a laser interferometer network that would provide better guidance on regional internal ice stress and incipient deformation than the virtual buoy GPS grid that uniq has been building. In past years, we have seen massive leads open up overnight from the easternmost tip of Banks Island (a repeat boundary condition) all the way to the New Siberians, ditto from Morris Jesup. We calculated a lower bound on crack propagation of 45 km/hr.

This is more of a factor mid-winter when the ice is thick and more brittle from the cold. Right now, the very extensive new ice that has formed between the summer minimum and the Siberian shore is incapable of resisting ongoing rotational shear. So it does not participate in that now but it will later as it becomes rigid.

In the vast subject of differential equations, people have been talking for centuries about complications introduced by abstract boundary conditions. In the context of Arctic sea ice, that is meant literally: fixed land encircling the basin and constraints it imposes on ice motion.

When an irresistible force (strong winds blowing against 7.1 m sq km of ice) meets an immovable object (like Kotolny Island), something has to give. And it's not the island. Up to a point, solid ice in the Laptev will inhibit the kind of ice motion we have seen the last week. Beyond that, enormous brittle fractures will become more frequent, putting equipment, people and the Polarstern itself at some risk.

There's a golden opportunity right now because of the unusual persistence and uniformity of ice pack rotation, to determine what (possibly non-unique) arrangement of high and low pressure gives rise to it. Simplistic notions such as the signature of the NAO pressure pattern are wholly inadequate to explain what we are seeing; it will require a more synoptic view of winds and the non-intuitive response of the ice to it that was already noticed on the voyage of the Fram.

Conversely, any theory of ice pack rotation will have to explain cases when the proposed pressure pattern does not result in rotation (or in ccw rotation). Indeed, one of the stated goals of Mosaic is a predictive model 5 days out for ice motion.

This is an instance of a truly massive body rotating nearly frictionlessly like a spinning ice puck near the axis of a rapidly rotating sphere where the coriolis and centrifugal forces are strong, so is different from familiar mid latitude air cyclones and the like.

For example, if the earth were rotating clockwise as seen looking down at the north pole instead of the 4 billion years of ccw, would TransPolar Drift reverse direction? And what about the AMOC:

https://www.livescience.com/62405-what-if-earth-rotation-reversed.html
https://mpimet.mpg.de/en/communication/news/focus-on-overview/retrograde/
« Last Edit: November 06, 2019, 11:25:15 PM by A-Team »

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Re: MOSAiC news
« Reply #216 on: November 07, 2019, 05:51:10 PM »
Polarstern "ship time" has finally been explained (below). The policy seems odd ... so many changes when they are trying to keep people on board on regular meal and work schedules. Meanwhile  mosaic_multisensor tracking, onboard meteorology and all the buoys are all on UTC?

The first icebreaker to meet the Polarstern for resupply and personnel exchange will be the Kapitan Dranitsyn, a similarly-sized vessel at 129 × 26m that is used for AARI research, passage escort and tourism currently in Murmansk. Its call sign on sailwx is UCJP; we will be eagerly following its track through the ice and inevitable damage during docking to the Fortress floe. However it may shut off its GPS beacon like the Akademic Fedorov did or at least dumb down its location to 1 dp.

AWI launched another Mosaic buoy nearby at 85.93 118.64 on Nov 6th, the 17th of the ice-tethered IT type (IMEI -7705700). These just report position and surface air temperature. There are currently 98 Mosaic buoys of which 8 have already failed.

Today saw an uneventful continuation of the last few daysof quasi-rotational motion, ie easterly drifting longitude at constant latitude (perspective animation), though OsiSaf ice motion is starting to act up, possibly bringing in shear in the next few days.

The real craziness was in very early October just before docking and then again between Oct 18-19 when the southern part of the floe seriously rearranged itself.

Currently the Polarstern is tied up at 85.9º,116.4º at 22:00 on Nov 7th, with mild wind and cold temperatures. The farthest north the Mosaic floe has drifted is 86.0º for 15 hours on Nov 5th. From where they are now, nearing the fast lane of the circumpolar drift, it doesn't seem likely that they will ever get closer to the Pole than they were on the 5th.

Following this on the latest OsiSaf amounts to drawing a circle from the pole out to the current latitude of the ship on OsiSaf, then observing whether the nearest gridded OsiSaf ice motion vector points inward relative to the tangent. If not, the Polarstern is gaining longitude but losing latitude.
« Last Edit: November 08, 2019, 12:35:49 AM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #217 on: November 07, 2019, 10:11:53 PM »
Some expansion, mostly on the western side during day307-8. All seems calm since then. One or more buoys failed to report day310hr11-12.
deformation test, day306-311 click to run
« Last Edit: November 07, 2019, 10:19:53 PM by uniquorn »

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Re: MOSAiC news
« Reply #218 on: November 08, 2019, 11:53:32 AM »
update on mosaic smb01-04 ice thickness data.
https://www.cryosphereinnovation.com/384820 (edit the imei for other buoys)

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Re: MOSAiC news
« Reply #219 on: November 08, 2019, 06:17:46 PM »
One of this morning's sentinel images with mosaic Pbuoy overlay.
This time using the final frame of a very large 2 frame macid animation and using further scaling and rotation to match the sentinel jpg graticule. click to run.
« Last Edit: November 08, 2019, 06:26:27 PM by uniquorn »

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Re: MOSAiC news
« Reply #220 on: November 08, 2019, 10:52:55 PM »
Quote
Measuring along the 120º longitude between 85 and 86º gives 2712.58 pixels. On the WGS84 ellipsoid, this distance is  111682 meters.  Thus the scale on S1AB images here  is 41.17 meters per pixel or reciprocally 24.289 pixels per km.

Very nice!

Cropping down but not resizing (which omits an outlier buoy in upper right), then drawing concentric circles in 5 km radial increments out to 40 km centered on the moored Polarstern (white arrow), we see this class of buoys is somewhat unevenly distributed about the base ship and not overtly co-located with ice surface features resembling the Mosaic floe.

Three Sentinel images surfaced again today (lower left). These show moderate en bloc motion over the scene uniq used, again equal parts zonally (eastward) and  southerly meridional (motion diagonally away from the 86th parallel) that can't be inferred from the 1 dp GPS data Mosaic provides to the public.

The green inset shows interferometry of the three times in the coordinate frame of the Polarstern. The Fortress area again stands out as a dynamic area (pink blob), as does a small lead (pink diagonal, upper right). The last 20 hours had subdued winds and (considering it's the Arctic) moderate temperatures. Click to see graphic at full resolution.

  85.9  115.9 19-11-08 20:00    7  360    -21.5 1017.3
  85.9  116.3 19-11-08 00:00    5   80    -26.2 1026.1

The collection of Sentinel radar overage of the Mosaic floe now consists of 57 times over 38 dates. Thanks to sailwx, a column for unix time was added; this is needed to determine time intervals. The ship reports once an hour on the hour whereas the Sentinel scenes are timestamped to intermediate minutes appropriate to the orbit.

Using database columns, it is easy to build links to the nullschool GFS display closest to the time of the Sentinel scene, showing the Polarstern's current location as the green circle along with the data popup. The GFS comes in 3 hour increments but if the url is not one of these UTC times, the link is resolved automatically to the nearest GFS time.

What relation GFS modeled wind speed, wind direction pressure and temperatures bear to actual precision on-site measurements remains to be determined. A big part of the problem in determining how ice responds to the wind (eg, the turning angle) has been poor quality, poor resolution data, often atypical coastal.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2000GL011495
https://pdfs.semanticscholar.org/5607/9c05753becd4c26a9d52b6f53d90d20fca45.pdf
« Last Edit: November 09, 2019, 12:11:43 AM by A-Team »

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Re: MOSAiC news
« Reply #221 on: November 09, 2019, 09:02:08 PM »
The photogrammetry needed to determine the lat,lon of the Polarstern more accurately than Mosaic is providing can be obtained by reading the position directly off the ship's image off Sentinel-1AB imagery (very large files a very long ways from the Pole origin of coordinates).

In terms of reducing error, the angle and distance from a convenient known location such as 86º,120º can be measured very accurately (and consistently by leaving tool end fixed while processing a whole stack of S1AB). Changing the anchor or angle by one pixel provides a measure of robustness of final calculated values.

The side-angle-side triangle computation provides arbitrary accuracy so no error arises there. One remaining issue is that S1AB are rarely on the hour, unlike buoys whose GPS positions are provided to Iridium databases to the high accuracy necessary to measure deformation.

The daily OsiSaf picture provides the best single overview of Arctic Ocean sea ice conditions; it shows sea ice concentration (open water, dodgy ice, thick ice) as well as the 48-hr ice motion. Things are a bit crazy right now in the Wrangel Island area with fragile ESS ice being pushed strongly away.

This doesn't immediately affect the Polarstern which had another day of smooth sailing almost due south. However the changing wind pattern could seriously wrench the ice pack around. Indeed on 2019-Nov-09 at 1900 UTC the ship is zig-zagging a bit west at constant 85.8 latitude so something is up.

The OsiSaf/AMSR2 template template below is easy to use. Save, open in gimp, activate the lat,lon overlay, paste in an entire Osisaf (it will automatically register itself), and autocrop by the template to discard extraneous regions.

On a throwaway layer, draw in the longitude line using the amsr 1º guidelines in Siberia. Here the trick is to continue on through the Pole until the guidelines resume in Canada -- this avoids finding the Pole pixel. Then measure the 85-86 distance and proportionately reduce for 1dp accuracy on latitude. Finally put a star at the Polarstern's position from sailwx on the OsiSaf layer. Discard amsr2 and throwaway layers, crop and resize fit for purpose. Because the product is usually saved as png, the xcf format of gimp will remain unchanged as a template for the future,
« Last Edit: November 10, 2019, 09:35:20 AM by A-Team »

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Re: MOSAiC news
« Reply #222 on: November 10, 2019, 01:37:10 PM »
Relatively clear weather for the mosaic team today giving an opportunity to use worldview brightness temperature(band15,Night) Suomi NPP VIIRS. Two temperature ranges have been chosen. The first to show the large leads to the north and east. The second much narrower band is an attempt to locate the Polarstern. click to run resized
Wide band, https://go.nasa.gov/33A1gQ6
Narrow band, https://go.nasa.gov/33A16bs

A very good rammb animation here of the state of the ice close to the pole by Blumenkraft 
« Last Edit: November 10, 2019, 03:41:53 PM by uniquorn »

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Re: MOSAiC news
« Reply #223 on: November 10, 2019, 04:57:18 PM »
This doesn't immediately affect the Polarstern which had another day of smooth sailing almost due south.

South?

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Re: MOSAiC news
« Reply #224 on: November 10, 2019, 10:21:59 PM »
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south?
Right. It's confusing but all directions are south from the North Pole, even 'up' which we are accustomed to think of as north on maps. Today the Polarstern held its latitude (southness) at 85.8º but slipped back 0.4º to larger longitude instead of drifting towards the 0º longitude Fram as intended.

Polar coordinates are the natural choice because physics associated with rotation through the earth's axis then has a simpler description. Ditto using the sun as the center for the solar system vs epicycles. All has to do with conservation of angular momentum. Problem is, pixels on device screens are square as in x,y. Money cannot buy a monitor with r,θ wedgie pixels.

Compounding the confusion is the Polarstern voted to have north up, all the time, on all maps. So two buoys, 50 km apart, are shown with different norths. No thanks. There is a reason why 'Greenland down' is used in almost all satellite products: so you can overlay them without quality-destructive fractional rotations. Not using UTC for ship time? Another head-scratcher.

The easiest way to follow Polarstern movement is glance at the hourly lat,lon at the Polarstern's weather feed (which is mounted on a mast on the bridge):

https://www.awi.de/fileadmin/user_upload/MET/PolarsternCoursePlot/psobsedat.html

   Lat  Long  YY-MM-DD  UTC     Wind       T(C)  N   hPa
  85.8  116.3 19-11-10 20:00    6  170    -29.3     1022.7
  85.8  116.3 19-11-10 19:00    6  170    -29.1     1022.3
  85.8  116.3 19-11-10 18:00    6  170    -29.0     1022.1
  85.8  116.2 19-11-10 17:00    5  150    -29.6     1022.1
  85.8  116.2 19-11-10 16:00    5  150    -29.5     1022.0
  85.8  116.2 19-11-10 15:00    4  150    -29.4     1022.1
  85.8  116.2 19-11-10 14:00    4  150    -29.0     1021.9
  85.8  116.1 19-11-10 12:00    4  150    -29.8     1021.9
  85.8  116.1 19-11-10 11:00    5  160    -28.8     1021.8
  85.8  116.1 19-11-10 10:00    4  120    -26.7     1021.5
  85.8  116.1 19-11-10 09:00    3  110    -26.4     1021.5
  85.8  116.1 19-11-10 08:00    3  110    -26.3     1021.1
  85.8  116.1 19-11-10 07:00    2  100    -26.2     1020.8
  85.8  116.0 19-11-10 05:00    3   50    -24.0     1020.3
  85.8  116.0 19-11-10 04:00    4   40    -25.2     1020.4
  85.8  116.0 19-11-10 03:00    5   30    -25.6     1020.2
  85.8  116.0 19-11-10 02:00    4   40    -26.3     1020.0
  85.8  115.9 19-11-10 00:00    7   20    -27.4     1019.9
  85.8  115.9 19-11-09 23:00    7   10    -28.0     1019.7
  85.8  115.9 19-11-09 22:00    6  360    -27.8     1019.6
  85.8  115.9 19-11-09 21:00    6  360    -27.9     1019.7
  85.8  115.9 19-11-09 20:00    7  360    -28.0     1019.4
« Last Edit: November 11, 2019, 03:47:35 AM by A-Team »

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Re: MOSAiC news
« Reply #225 on: November 10, 2019, 10:25:12 PM »
Here is some further detail on the Polarstern and ambient ice dynamics in the Mosaic project area. Winds have been mild keeping stress on the ice pack minimal but that is due to change by noon tomorrow if GFS can be believed.

The peak sustained winds of 55 km/hr corresponds to about 15 m/s in the units used by AWI above. So that is about 3x the average wind speed of the recent weeks but in terms of force on the ice, more like the cube or ~27x for wind power density (2.4 kw/m^2 maximum).

The Polarstern, the world's fanciest buoy, is also a gigantic sail. While leads have surely frozen over in the area and ice on the port side is much colder than at the Oct 5th mooring, it is also more brittle but not yet much thickened.

Very little of the floe actually has equipment such as wx towers set up on it, though power and data lines run out to the three main deployment areas. The very fanciest ARM equipment stays in six containers on the bow of the ship and makes its measurements from there.

However, the near-disaster on Oct 18-19 shows that the Mosaic floe is already preconditioned to further fracturing as nearby massive fissures freeze up but never really reach full strength again.

It's not clear what it even means to 'follow the evolution of a single floe for a year" when the Mosaic floe has already undergone multiple significant demonstrable macro rearrangements not 10% into the cruise, unrelated to classical ice thermodynamic issues such as ocean-ice-air heat transfer they came to study.

While people onboard report constant noise from grinding ice, it may not be possible in the dark to sense relatively slow deformations like those seen in consecutive Sentinel scenes. The perspective and nadir views are 3x enlargements so about 14 meters per pixel over 3 hours 16 minutes of timestamp separation today. Thus changes of a few pixels off the Fortress area, if it happens at a steady rate rather than abruptly, are at tortoise speed.

Technical note: the nullschool GFS model below picks up the baton from the most recent OsiSaf in 3 hour increments and carries it forward another 100 hours. These are easily made by stepping the Polarstern position-aware url below with keystroke k, then taking whole window screenshots to build registered layers in gimp. The numerical values are then cropped out from image duplicates and layered over the tiled-up wind graphic after adjusting text height and expanding canvas width to match the main tile size.

https://earth.nullschool.net/#2019/11/09/1200Z/wind/isobaric/1000hPa/stereographic=-45.000,70.000,1350/loc=116.1,85.80
« Last Edit: November 10, 2019, 11:38:46 PM by A-Team »

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Re: MOSAiC news
« Reply #226 on: November 10, 2019, 11:48:39 PM »
Perhaps that is more ridging close to the polarstern.

South? It confused me too. Not happy with the blurred buoy positions on post #219 above here is a more accurate version using a larger buoy image and one rotation. Comparing the pentangle of buoys on the 86N line with the post above they do move almost due south. Confusing.
This image should include all the meereis mosaic buoys in the small area shown that are listed here which reported at 0400 UTC today. Lat/Lon positions are ~8mins earlier than the image. (click for full resolution)
« Last Edit: November 11, 2019, 12:01:48 AM by uniquorn »

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Re: MOSAiC news
« Reply #227 on: November 11, 2019, 01:49:36 AM »


Re: MOSAiC news
« Reply #224 on: Today at 10:21:59 PM »
LikeQuote
Quote
south?
Right. It's confusing but all directions are south from the North Pole, even 'up' which we are accustomed to think of as north on maps. Today the Polarstern held its latitude (southness) at 85.8º but slipped back 0.4º on longitude instead of drifting towards the 0º longitude Fram as intended.


So latitude stayed at 85.8º so it moved neither N or S, but its longitude increased so to my mind that means they're drifting E?

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Re: MOSAiC news
« Reply #228 on: November 11, 2019, 04:35:45 AM »
Right. They got as far north as 86.0º. At midnight, the Polarstern is currently at 85.9  116.3 on 19-11-11 at 00:00 UTC. They got as far east as 135.8. lt's all tabulated for you in the csv attached above for the Sentinel image catalog or in nrt at the url above.

It looks from uniq's map that one of the buoys is actually on the Mosaic floe itself, on the northwest corner. Since it was closest to the Polarstern on Nov 8th, it is closest to the Polarstern now since everything is moving in lock step.

So copying out the current IABP positions of all buoys in the Arctic Ocean right now and grepping down to the 92 active Mosaic ones (just replace 'cr Moraic' by 'tab Mosaic' and sort on column G), then inserting the current PS lat, lon and sorting on lat, then lon the picture below emerges for buoy names closest to the ship. Here we need the PS position to more dp, as described a few posts above.

Quote
A very good rammb animation here of the state of the ice close to the pole by Blumenkraft
https://forum.arctic-sea-ice.net/index.php/topic,2649.msg236185.html#msg236185
Passing clouds can be cleared away by hitting the 'average' button on gimp for the 60 gif frame stack. It's interesting to see utility of WorldView satellites continuing into the winter.
« Last Edit: November 11, 2019, 12:21:05 PM by A-Team »

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Re: MOSAiC news
« Reply #229 on: November 11, 2019, 02:06:31 PM »
Passing clouds can be cleared away by hitting the 'average' button on gimp for the 60 gif frame stack. It's interesting to see utility of WorldView satellites continuing into the winter.

Wondering if there is a workflow for that. Thanks for the hint anyway, A-Team. When i find the time... ;)

In other news, according to the podcast, there is a fish cam! Anyone ever saw footage of that thing?
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Re: MOSAiC news
« Reply #230 on: November 11, 2019, 03:44:45 PM »
Quote
fish cam? bridge radar? gps? helmholtz? cruise report? ms piggy? ROV ice bottom?
I've not even seen a still. Can you not wait until 2023 when Pangea is unblocked and papers first start appearing? Mosaic has very restrictive top-down control of  ( :) ) information, trickle-down. Just because you paid 100% of expedition costs with your taxes doesn't give you any right to know what they are doing.

Another AWI snow buoy was pronounced dead this morning by IABP, the 8th such announcement that went unannounced. This one was defective from the day of installment, hardly ever reported air or snow temperatures but worked for 26 days as a GPS buoy.

They should really let the buoys start reporting to Iridium on shipboard to see if the sensors are working rather than wasting helicopter resources deploying. Or maybe test them back in Germany? The IABP record shows they did neither.

This didn't start with Mosaic -- the Arctic buoy program has always been a joke. A thousand second-hand iPhones dropped from a plane could do better tracking ice.

The Polarstern continues to drift back and forth, up and down. From the 3 Sentinels this morning, the ship can be seen moving north along the 116.4º meridian. Displacements are unremarkable: at 126.5 pxls between the 03:11 and 06:25 which pencils out to 2.8 km in 3 hrs 14 minutes or 20.8 km per day.

Since the last S1B, the ship has moved 0.2º east while holding the same latitude 85.9. Winds predicted by GFS seem to be picking up at the ship: they are at 14 m/s now and expected to reach 15.3 m/s or 55 km/hr.

This is close to the worst winds the ship has experienced so far, back on Oct 8th winds reached 60.7 km/hr according to sailwx. The attached graphic shows the wind speed distribution; the attached csv has columns the speeds in km/hr, m/s and knots. These October winds were being called gale force at the time, fair enough:

2019-Oct-08 0600   85.0   136.0   56.9
2019-Oct-08 0500   85.0   136.0   56.9
2019-Oct-08 0400   85.0   135.9   60.7
2019-Oct-08 0300   85.0   135.8   60.7
2019-Oct-08 0200   85.0   135.7   56.9
2019-Oct-08 0100   85.0   135.6   56.9
2019-Oct-07 2300   85.0   135.3   56.9
2019-Oct-08 0600   85.0   136.0   56.9
2019-Oct-08 0500   85.0   136.0   56.9
2019-Oct-08 0400   85.0   135.9   60.7
2019-Oct-08 0300   85.0   135.8   60.7
2019-Oct-08 0200   85.0   135.7   56.9
2019-Oct-08 0100   85.0   135.6   56.9
2019-Oct-07 2300   85.0   135.3   56.9
Quote
A gale force wind can be defined as a sustained strong wind, registering between 7-10 on the Beaufort Scale, which indicates wind speeds of 50 - 102 km/h

It's not entirely clear at what height above the ice these winds are measured and modeled. Usually wx tries to get clear of surface topography but that is exactly where wind stress is applied to the ice. The Polarstern has lost 0.4º of longitude in the last 14 hours; this is interesting/confusing because it suggests a wind coming from 180º (measured at the ship) blows the ice due east.T

The 14 m/s is just barely over 50 km/hr so a few more hrs will bring them into a sustained gale force stress regime. GFS today shows the winds peaking at 54 km/hr at 03:00 UTC from 205º on the 12th and not abating until 09:00 tomorrow. The S1B's will cover the ice response quite well.

  85.9  116.7 19-11-11 15:00   16  180
  85.9  116.7 19-11-11 14:00   14  180
  85.9  116.6 19-11-11 13:00   14  180
  85.9  116.6 19-11-11 12:00   13  180 [GFS predicted this perfectly: 13.9 m/s 175º, see above]
  85.9  116.6 19-11-11 11:00   13  180
  85.9  116.5 19-11-11 10:00   11  170
  85.9  116.5 19-11-11 09:00   11  170
  85.9  116.5 19-11-11 08:00   10  170 
  85.9  116.5 19-11-11 06:00   11  170   S1B 06:27
  85.9  116.4 19-11-11 05:00   10  160
  85.9  116.4 19-11-11 04:00    8  160   S1B 04:49
  85.9  116.4 19-11-11 03:00    9  160   S1B 03:11
  85.9  116.4 19-11-11 02:00    9  180
  85.9  116.3 19-11-11 00:00    7  190

The offset is mildly confusing: the 120º is at 75.00 on Sentinel images according to gimp and imageJ angle tools as appropriate to 'Greenland down'. So the offset is 45º, meaning the 116.4 should be drawn at 71.40º towards the pole which is ten thousand pixels off the image.
« Last Edit: November 11, 2019, 06:00:27 PM by A-Team »

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Re: MOSAiC news
« Reply #231 on: November 11, 2019, 03:58:41 PM »
Can you not wait

NOOOOOOO!  ::)

It's a shame. I will write them!
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Re: MOSAiC news
« Reply #232 on: November 11, 2019, 05:40:17 PM »
No question, they are putting in long hard work days on the ship. However there is large support team onshore including many idle grad students, post docs and senior ice researchers (who mostly departed on the AF because lab techs stay on to maintain instruments).

Some of what we do hear strains credulity: stable ice dynamics (the satellite is wrong), launching a giant weather balloon in gale force winds (the ship weather station is wrong) and so on.

The top priority for us is simply hourly GPS position and bearing data for the Polarstern. As measured, to 4-5 dp and tenths of a degree. Nobody goes to sea without this basic technology.
 
In my view, sea ice forums are not perceived as a credible threat. It is rather scientists from N-ICE2015 who pose the real danger. They would know exactly what to do with the data if there were any: process and submit journal papers, thus scooping Mosaic players before they could even get their toes thawed out. That would be a terrible tragedy that dwarfs important climate change  information that might emerge sooner. That's the mind-set behind all the secrecy.

Putting academic games aside, what will tomorrow morning's satellite show? The ice along the Polarstern's meridian is experiencing high but fairly uniform wind stress that is not conducive to dangerous shearing. However to the east and west of its latitude, the wind is minimal. This suggests strong tensile forces to the east (big leads opening) and strong compressive forces to the west (ridging, over-rafting).

The current anti-cyclone, like so many of them, is not rotating about the geographic north pole but rather the pole of inaccessibility, the reason being less oppressive boundary conditions. Starting from the Polarstern's current position, it is easy to make make wind stress transects meridionally, zonally, or radially wrt the anti-cyclone center

The first of these shows a moderate gradient along air flowlines; the second which is similar to radial shows almost no wind gradient in direction or speed. Thus locally, ice dynamics may be fairly minimal in the immediate vicinity of the Polarstern. (However effects can propagate long distances in brittle sea ice.)
« Last Edit: November 12, 2019, 02:13:15 AM by A-Team »

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Re: MOSAiC news
« Reply #233 on: November 11, 2019, 11:22:27 PM »
Z axis shows the % distance change per hour of 23 Mosaic buoys, day311-315. Some different movement on day312, mostly to the north. Perhaps brittle is the right description.
edit: updated downthread
« Last Edit: November 12, 2019, 06:42:42 PM by uniquorn »

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Re: MOSAiC news
« Reply #235 on: November 12, 2019, 02:26:30 PM »
Nice way of tracking Polarstern!

The first image below brings the next frame of the time series, the 00:42 of the 12th, into Sentinel position which involves a cw rotation of 105º to bring the 130th meridian into vertical position. That is needed to extend the canvas downward so that the 86º latitude circle can be drawn. (RAMMB shows the 87.5; two latitudes must be included for the radial scale to be determined accurately.)

The image shows the Polarstern position data from sailwx and ship meteo for 00:00 and 01:00 UTC. The agreement is ok with the lights of the ship show it to be at 85.95º, 117.37º (=45.00 + 72.37 measured) versus the rounded off 86.0, 117.2 of the low accuracy GPS.

It appears that no Sentinel coverage will be provided following the sustained gale force winds; processing delays at PolarView happen but are not common. It is not possible to see down to the ice on the Rammb which is working at 700nm in the far red part of the visible spectrum. ImageJ allows color to be set by wavelength; a putative 700 nm square is included.

The nearest Sentinel for Nov 12th is well to the west of the Polarstern and is shown below only to illustrate the extensive fracturing that can occur in Arctic sea ice. The inset shows the width of an 1100 km feature (at the 41m/pxl scale of the inset) can exceed a kilometer.
« Last Edit: November 12, 2019, 05:51:54 PM by A-Team »

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Re: MOSAiC news
« Reply #236 on: November 12, 2019, 04:21:55 PM »
Well, RAMMB is already done updating. Stuck at GMT 0:42.  :'( :(
« Last Edit: November 12, 2019, 07:05:53 PM by blumenkraft »
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Re: MOSAiC news
« Reply #237 on: November 12, 2019, 07:01:09 PM »
5 mosaic buoys on iabp have files of incorrect length today, 3 of them were in the group used recently for the deformation test. In particular, 7509680 was a nice outlier to the south east for showing distance change. It's been replaced with 6344810 a little closer in.
This animation updates the one previously upthread using tighter lat/lon and a smaller z axis, day311-316(today). As the ice thickens there is likely to be less movement.

I think some of the movement shown using this method is due to a small distance change causing the delaunay triangulation to connect the buoys in a different order which will give an inaccurate, possibly meaningless, distance change in some of the central points. Using less buoys would reduce that possibility, as would diving deeper into the code. So, probably less buoys ;)
or less animations :)  Removed


« Last Edit: November 13, 2019, 09:50:47 PM by uniquorn »

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Re: MOSAiC news
« Reply #238 on: November 14, 2019, 11:53:35 AM »
This picks up at 0:42Z on the 12th.  There's a 16 hour jump at the beginning due to no imagery available.
Click to run. Contrast boosted for detail.

« Last Edit: November 14, 2019, 12:38:10 PM by JayW »
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Re: MOSAiC news
« Reply #239 on: November 14, 2019, 03:35:33 PM »
The first three images show what happened in the vicinity of the Polarstern during the gale (defined as sustained winds over 50 km/hr) that peaked at 16:00 UTC on 11 Nov 19. Some very large leads opened to the east and widened again overnight but have not impacted the Mosaic experimental area too much at this point.

The first gif has cut-outs on the Nov 11th to allow the 13th and 14th to show throught. The Polarstern is in the lower right corner of the second time series.

Three S1AB scene were taken on the 11th, none on the 12th, only a rare S1A on the 13th and a single S1B on the 14th. It is difficult to understand priorities at ESA/Copernicus. Only scenes in the sensor mode EW_GRDM_1SDH will appear on PolarView; the Copernicus portal lacks polar ordering views.

The omission on the 12th is only the 4th gap in coverage since Oct 1st during which 66 scenes have been provided. The only other tools we have are RAMMB as above, Band 31-night on Terra and Band 15 VIIRS on Suomi but these are usually plagued by cloud cover.

Heat release from the ocean to the air as visualized in passive infrared bands will only correspond approximately to active S1AB radar which is imaging something entirely different, beam return as inhibited by dielectric (salinity) but enhanced by surface roughness. The black and white stars correspond to the Polarstern's coordinates on this date.

More buoys are failing to report. The number soared to 15 as a batch of Chinese TUT buoys went offline very close to the same time for unknown reasons. These leaves 84 still working though some of those report with inexplicable and growing delays. At this rate, not a single Mosaic buoy out of a hundred will survive past 20 May 2020. These buoys are very important in extending the project's reach beyond the immediate drift of the Polarstern.

The current location is at a record northerly latitude (not quite to Nansen's 86.22 but farther than the Fram's 85.92) but the drift is again away from Svalbard. Nothing resembling the weather pattern characteristic of transpolar drift has set up yet per OsiSaf.

86.2  118.3 19-11-14 13:00    9  200    -13.8
« Last Edit: November 14, 2019, 04:05:11 PM by A-Team »

blumenkraft

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Re: MOSAiC news
« Reply #240 on: November 14, 2019, 06:46:33 PM »
Meet Trude Hohle.

(She might have the most German name in the history of German names.  ;D)

Imagine your job is to protect your crew by spotting and scaring away polar bears... Bravery for science!
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blumenkraft

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Re: MOSAiC news
« Reply #241 on: November 14, 2019, 07:49:57 PM »
RAMMB-SLIDER Day&Night vs M15 band.

Makes a good combination to show cracks in the near vicinity IMHO.

Click to play.
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Re: MOSAiC news
« Reply #242 on: Today at 03:10:58 AM »
Decent Suomi band 15 on Nov 13th, click to enlarge. The Polarstern is just a bit under the clouds. They still have no more than a good dusting of snow.

Not clear why PS complains so much about the cold when it is far more pleasant than Chicago at 41.9º N (where I had a pre-dawn Sunday paper route as a kid).