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Threebellies

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Re: MOSAiC news
« Reply #100 on: October 09, 2019, 11:27:28 PM »
Quote
This search for a suitable floe is ongoing

This has become a common problem for placing instruments on the Arctic ice. It also means measurements are being done under unrepresentative conditions.

Using sampling to ultimately estimate the conditions of the entire Arctic via statistical analysis requires representative (usually random) sampling but this is no longer possible. The result is likely over estimation of sea ice thickness and stability.

Not only that, it’s indicative of a paradigm shift. If ice conditions aren’t good enough to take proper samples, well, that suggests we’re a lot closer to a BOE event than some would acknowledge.

Voyages should be done like this yearly, I wish we had this back when there was actually sea ice and not slush up there.

uniquorn

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Re: MOSAiC news
« Reply #101 on: October 10, 2019, 12:30:10 AM »
crop of the mosaic multisensor map, oct7-8 showing ~20km south eastward drift since yesterday. An interesting start to this expedition. Red and white bar at the top is 20km
« Last Edit: October 10, 2019, 12:43:08 AM by uniquorn »

jdallen

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Re: MOSAiC news
« Reply #102 on: October 10, 2019, 07:28:31 AM »
It's not entirely clear that melt season is over in some parts of the Arctic Ocean.
<snippage>
It's pretty clear from the temperature data, the extent/area data and the sensor data from sources like Mosaic that the transition from melt to refreeze is no where near as distinct as it was prior to the last decade or so.

We are already seeing Arctic breakouts.  Heat intrusions above 75N are continuing pretty much unabated.  I suspect Mosaic will not show signs of either significant thickening or serious expansion of the pack into the peripheral seas for quite some time.
This space for Rent.

A-Team

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Re: MOSAiC news
« Reply #103 on: October 10, 2019, 10:14:34 AM »
Quote
transition from melt to refreeze is nowhere near distinct
Right. The 1D extent graphs don't capture geolocated nuances.

It turns out to be easy to pattern-match radar images of the Mosaic floe in early October back to visible images in Worldview in late September (before it all went dark) because in context, the floe moved as a mildly distorting rigid body over this time frame.

This enables convenient determination of the floe's provenance, daily displacements and deformations using the animation feature of WV on clear days back to 18 Mar 2019 when WV first had enough light.

Note the Mosaic radar archive goes back to Sep 8th and is cloud-free unlike visible. However its resolution is inconsistent, with a big jump on Oct 7th after the floe was selected, plus it suffers from a now-irrelevant ship track overlay. In #74, the floe is tracked back to Sept 21 in radar.

https://forum.arctic-sea-ice.net/index.php/topic,2906.msg232032.html#msg232032

However PolarView goes back even farther with its Sentinel archive. However visible and near infrared carry other information such as surface temperature, insolation history, proximity to algal blooms and wildfire soot deposition.

Because this floe will be so intensively studied over the next year, it is important to walk it back in time to better understand its 'initial state' in the Mosaic project.

The last 30 days of sea ice motion suggest that the floe has experienced very little net tendency towards resuming TransPolar Drift. The floe may have been in sub-100% concentration (light blue in OsiSaf) in mid-Sept and earlier.
« Last Edit: October 10, 2019, 12:32:29 PM by A-Team »

A-Team

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Re: MOSAiC news
« Reply #104 on: October 10, 2019, 12:47:35 PM »
Mosaic buoy data to date can be checked here. There are 16 surface velocity profilers so far; the downloads clean csv text files with hourly lat/lon to 4 decimals, drift speeds to 3 decimals in m/s, and surface temperature to 1 decimal.

However they don't triangulate the buoys nor give the ensuing Delaunay deformation over time, for which 16 Excel sheets is ideally suited (and Goog Earth Pro freeware for the graphic animation).

This is an example of where a forum member could add value to Mosaic by using the online distance tool that Uniq provided earlier. GPS positions are always given relative to the WGS84 ellipsoid of revolution rather than the earth sphere or actual geoid (available as the first 100,000 terms of a spherical harmonic expansion).

The AWI help desk writes that a more interactive version which will be online in mid November. [Hallo? Bei uns wäre diese grundlegende Softwareaufgabe erledigt gewesen, bevor das Schiff gesegelt wäre! Zur Sicherheit muss der Polarstern nahezu in Echtzeit wissen, wie sich die Belastung im Eis aufbaut, nw?]

I'm mildly astonished that oceanographers have not set up an online tool that does this.The triangle math is from the Babylonians 4000 bce, the rest was published in 1934 by a Russian descendant of a French officer captured during the Napoleonic invasion of 1812. It is not especially computationally expensive: the algos are seasoned github deposits for video gamer programmers.

The geometric set-up is very similar to USGS arrays to monitor nrt tectonic plate collision in Nevada and so earthquake strain in southern California (though some of that is interferometric as displacements are in microns). This is the PS's concern as well: sudden opening of leads and rapid formation of pressure ridges.

I could see it taking me a couple hours to start supplying the PS with nrt continuum mechanics in its immediate vicinity (but surely they have laptops on board?). Because the buoy gps is so accurate, this might improve on whatever deformation overlay they have on PS bow radar, though that would be really rt instead of hourly.

The issues are kriging up the resolution and assimilating the observed current system of S1 rifts. The ambient ice has been under extensional tension rather than compressional.

The explanation for the visualization delay must be that buoy arrays have rarely been deployed in ice: the Arctic Ocean has long been seriously under-instrumented. So three cheers for Mosaic's deployments -- this should have been done every year since Iridium went commercial in 1998.

Found a buoy forensics match to the first deployment question in #40 and chased down how we got to the words 'buoy' and 'die Boje' (plural Bojen). The English pages at Mosaic are sometimes delayed a few days.

https://data.meereisportal.de/gallery/index_new.php?active-tab1=method&buoytype=all&region=all&buoystate=all&expedition=MOSAiC&submit3=Anzeigen&lang=de_DE&active-tab2=buoy
« Last Edit: October 10, 2019, 05:00:54 PM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #105 on: October 10, 2019, 08:40:25 PM »
Nice detective work. Don't we need to see the overall buoy set up before launching into continuum mechanics? edit: not that I know how to do that ;)
Based on today's multisensor map I think I've located a buoy on or very close to Polarstern for the last few days. iabp 300234068213470. I'm not sure if this is value for MB but here is it's drift track since records started.
GFS forecast (from Nullschool) shows a yo-yo swing in temperature in the vicinity of Polarstern over the next 24 hours or so.

By 12 UTC on 8th Oct, a plume of mild arrives up from Svalbard, yielding temperatures slightly above 0 C but it is short lived and 12 hours later at 00 UTC on 9th Oct, it forecasts temperatures below -10 C as cold air is advected across the Pole from the American side towards Russia.
warmest temp was -2.4C, still quite warm. Of course, it might be sitting in the hold somewhere so the temps might not be relevant. The drift should be valid though.
edit: tech note: gif is optimised to reduce size in gimp, it may be necessary to deoptimise if downloaded. OT they must be an amusing bunch at iabp
« Last Edit: October 10, 2019, 09:38:10 PM by uniquorn »

uniquorn

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Re: MOSAiC news
« Reply #106 on: October 10, 2019, 09:20:19 PM »
Thanks to meerisportal and the mosaic team, here are their prepared buoy charts.
Quote
Grosfeld, K.; Treffeisen, R.; Asseng, J.; Bartsch, A.; Bräuer, B.; Fritzsch, B.; Gerdes, R.; Hendricks, S.; Hiller, W.; Heygster, G.; Krumpen, T.; Lemke, P.; Melsheimer, C.; Nicolaus, M.; Ricker, R. and Weigelt, M. (2016), Online sea-ice knowledge and data platform <www.meereisportal.de>, Polarforschung, Bremerhaven, Alfred Wegener Institute for Polar and Marine Research & German Society of Polar Research, 85 (2), 143-155, doi:10.2312/polfor.2016.011.
Now to set them all up from the same start date/time and see where they all are :)
https://data.meereisportal.de/gallery/index_new.php?active-tab1=method&buoytype=all&region=all&buoystate=all&expedition=MOSAiC&submit3=display&lang=en_US&active-tab2=buoy
(english version)
seem to have lost the buoy names somewhere....fixed
« Last Edit: October 10, 2019, 09:35:12 PM by uniquorn »

uniquorn

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Re: MOSAiC news
« Reply #107 on: October 10, 2019, 10:12:16 PM »
A brief break in the clouds. Worldview, mosaic rough location, 84.9N 135.7 (no timestamp on worldview) https://go.nasa.gov/3286OQU

A-Team

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Re: MOSAiC news
« Reply #108 on: October 11, 2019, 12:16:54 PM »
Quote
WV graticule? need final set of buoys? buoys too near the Polarstern? Physics of materials?
Spectacular VIIRS above ... but when I went to the link, it had been over-written by something unrecognizable. That happens all the time at WV as swath updates roll in. I suppose the bright networks of veins are leads (resp. thin ice) with warmer water showing through. These might be worth mapping as lead openings are recurrent weaknesses.

The 43 page explainer for the Visible Infrared Imaging Radiometer Suite is here:
https://lpdaac.usgs.gov/documents/134/VNP03_User_Guide_V1.2.pdf

WorldView doesn't do graticules well, 80º is the first latitude out from the pole with 30º increments on longitudes. Better if NASA provided options for controlling the OpenStreetMap vector graticule and fixed code so animations captured it. It's possible but inconvenient to capture the timestamp on a per swath basis which is critical to synching with other satellites.

While WV does have very accurate mouse-over lat/lon in the corner, those don't stay tied to a floe after image save or screenshot. Mosaic Multisensor offers a very nice graticule on their higher resolution images (from Oct 7th on).

For WV, if your save includes long lines intersecting the 80º circle, that chord length is enough to accurate rescale AMSR2_Large and capture its graticule as overlay for 75º and 85º plus 1º longitude increments.

/=/=/=/=/=/=

The ship itself is one big fancy drift buoy, not only reporting its GPS but also whatever parameters those six containers of atmospheric instruments in the bow are recording. Plus its azimuthal heading which the surface velocity profilers do not provide.

A rigid body can undergo translations (GPS) and rotations (azimuth changes) that are not relevant to the brittle failures of concern (opening and closing of leads, over-rafting of floes, slip-strike shearing and pressure ridges/keels).

Mosaic actually likes leads because they release ocean heat to the atmosphere and are important to study for overall energy flows, just not leads that cut LAN and power lines and strand personnel at field stations.

Taking any three buoys that define a good triangle (not co-linear, no overly acute angles), the lengths of the three sides and area enclosed do not change over time in a rigid ice pack. If the area increases, it means leads have opened under extensional forces; if the area decreases, compressional collapses have occurred.

If say 70 buoys are deployed, a goodly system of coupled triangles (the perimeter being the convex hull) emerges for monitoring regional ice deformation. Here ice brittleness increases non-linearly with colder temperatures. Since the SVPs record air temperatures at the ice surface and since the seawater underneath the ice is clamped to -1.7ºC, the temperature profile through say 2m of ice can be estimated.

Mosaic has two different buoy scales, high resolution local on and around the chosen floe and more sparsely regional. There aren't enough buoys out there to do the whole basin. There has been talk of large-scale air drops of passive devices like radar corner reflectors that would show up as points of light on Ascat etc. Hasn't happened.

Someone posted a great animation (can't relocate :() of the ice temperature profile behavior under an upper sinusoidal (seasonal) boundary conditions, plus an explicit solution of the governing heat equation. Thus if the a curve is fitted to the buoy's hourly temperatures, each term in its fourier expansion will have an exact solution -- and these are additive solutions.

However real ice has many issues such as surface snow and its complex aging status, frozen-in air bubbles, variable salinity inclusions, brine pockets, crystal dislocations, adherent algae and copepods etc etc meaning that the heat conductivity parameter isn't constant or known. So it is easier just to freeze in a string of thermistors below the buoy.

/=/=/=/=/=/=

We can do a lot better than that cramped meereisportal visual just with a drag-n-drop of all the buoy lat/lon columns onto google earth pro. The advantage of GEP is the liquid rescaling to any zoom, a free parameter for temperature or thickness and mouse-over popups; the disadvantage is there does not seem to be a digitized daily ice edge line around. However there is a way of auto-generating that from say the AMSR2 blue edge.

GEP barely pauses loading a kml file with 250,000 lat/lon waypoints. That would be 30 buoys reporting hourly for a year. Hourly is a bit much given slow drift speeds but it is great for dynamic triangles. There is very little overhead to drawing lines between buoy pairs with the same timestamp.

/=/=/=/=/=/=

The AMSR2 images below compare the ice edges on the Siberian side south of the Polarstern on Oct 10th for 2013-2019 (the 2012 is not provided by the UHH archive). The large format 3.125 km does notably better on growing landfast ice. This narrow strip is difficult to image because of the irregular coastline can occupy part of rectangular gridded pixels.

Clearly autumn 2019 is off to a very slow start; the magenta overlay line on earlier years shows how much open water is still left in the Laptev, the star at bottom shows the Polarstern location. I don't expect the 500 km reach of open water to freeze over any time soon because shallow shelf water been increasingly affected by Atlantification. The Laptev had frozen over completely in 2012-13 by the first of the year.
« Last Edit: October 11, 2019, 07:44:40 PM by A-Team »

macid

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Re: MOSAiC news
« Reply #109 on: October 11, 2019, 01:47:19 PM »
Animations of buoys drift speed attached, code on my github, it should be possible to take a set of buoys and calculate their movements respective of each other.. interesting idea

there's accelometer data in the buoy data as well, I assume this can be related to wave height or ice bits bumping into each other?

Also if anyone has good data files for ice concentration/movements please let me know. I saw AMSR2 has hdf files but they're a bit of a pain, preferably something with coordinates.

uniquorn

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Re: MOSAiC news
« Reply #110 on: October 11, 2019, 08:06:40 PM »
Good step forward on buoy analysis :).
polarstern temps for niall, half a yoyo
« Last Edit: October 11, 2019, 08:12:08 PM by uniquorn »

A-Team

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Re: MOSAiC news
« Reply #111 on: October 11, 2019, 08:28:37 PM »
Quote
should be possible to take a set of buoys and calculate their movements respective of each other
Quick and easy way to do that on a massive scale -- # of buoys and # of times -- is a database mail merging into kml template (keyhole markup language, human readable text like html), let Google Earth do the scalable display over a bathymetry background plus calculate all the distances and polygonal areas for you to very high WGS84 accuracy and then load it up on a web browser so clients don't need GE installed.

Just look at the attached txt file for the triangle ... it's so easy, it's so easy to parse it out and drop into their display engine.

The SVP buoy 2019P152_300234068218450_proc.csv weighs in at just 16 kb for 299 lines. The three buoy triangle, 1 kb. So not talking serious text wrangling here with a few dozen buoys for a year; in SV days our group was knocking out 16 terabyte based scientific displays, trillions of buoys.

« Last Edit: October 11, 2019, 09:36:02 PM by A-Team »

Niall Dollard

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Re: MOSAiC news
« Reply #112 on: October 11, 2019, 10:31:18 PM »
Good step forward on buoy analysis :).
polarstern temps for niall, half a yoyo

Thanks for that plot Uniquorn. So didnt quite reach positive values.

For yo-yo temperatures, it's hard to surpass the eastern slopes of the Rockies. Denver drop of 39.5 C in 36 hours !

blumenkraft

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Re: MOSAiC news
« Reply #113 on: October 12, 2019, 07:41:02 PM »
Life aboard the RV Akademik Fedorov

Link https://www.mosaic-expedition.org/mosaic-school-week-2/
Refugees welcome

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Re: MOSAiC news
« Reply #114 on: October 13, 2019, 01:18:15 AM »
Update: the differencing of successive days of AMSR2_large is an effective way of visualizing closure of the open gap between the Polarstern and the Siberian shoreline: central ice pack edge growth meets growing landfast ice. Growth of that is just now kicking in.

I was just barely able to scale down mosaic.multisensor to overlay the Polarstern drift path on the 3.125 km resolution AMSR2; this require downsizing the radar original to 0.45% to get the path scaled (no sign of TPD yet).

There are a lot of ways to slice and dice the buoy data, the first substantial nrt data set we’ve had to work with, other than satellite products, since the ice penetrating radar archive for Greenland. In past years, 0-1 buoys have been reporting, often defectively, in the entire Arctic Ocean whereas now we have a large active coupled buoy array in the vicinity of the Polarstern..

The data archiving is still a bit rough, for example the second set of buoys below don’t measure snow depth or ice thickness as their meereisportal table indicates. However provisional graphs of temperature and speed are provided as a convenience and updated daily.

The Polarstern itself behaves as a giant buoy since being stably moored on Oct 4th. No hourly database for it accompanies the others. The radar image archive shifted to high resolution on Oct 7th. The pixel dimensions shifted inexplicably from 3500 x 4304 to 3498 x 4302 between the 7th and 9th, causing stacking issues. (Inexplicable because the crop tool has a fixed-size checkbox in all known image software.) The timestamps are all 0500 UTC; lat/lon of the Polarstern are not provided in the extensive legend.

The Sentinel images have different pixel offsets each day. Lagrangian coordinates (co-moving with ship) are being used; they cause havoc with the graticule and drift course overlay. It's more common on satellite series to use fixed eulerian coordinates to illustrate floe and lead dynamic development.

https://data.meereisportal.de/download/buoys/photos/2019P191_deployment.pdf

The first set of RSAQUA-type SVP buoys was deployed by Chinese scientists. These measure GPS position every hour along with temperature. From lat/lon they derived displacements (not shown) by an unknown equation (vincenty? haversine?), from which speeds were determined hourly. These buoys do not carry a wave heave accelerometer. Tides in the open Arctic are too low and slow to give a reading.

I checked into measurement error. One degree difference in latitude on the WGS ellipsoid is 111,111 meters. The GPS is reported to 1 part in 10,000, meaning 85.1234º can barely be distinguished for 85.1235º. Thus the positional uncertainty is 11.1 meters which is inadequate for a cruise missile but plausible this far north.

In calculating items like the changing sides and angles of a delaunay triangulation array, no purpose is served by exceeding the accuracy of the data.

It appears the buoys do not track azimuth. That is, unlike a ship, there is no natural axis unless the floe itself is stably asymmetric. Rotation of the floe in which the buoy is frozen is thus difficult to disentangle from translation.

We have measured large floes spinning around and around in the Beaufort arm eddies in previous autumns. In the vicinity of the Polarstern, the ice is mainly moving en bloc. The arm is forming nor this month and will likely extend up the Alaskan coast to the Chukchi before turning north. The ice will not move in a gyre, it hasn't for over a decade.

A column for changing bearing angle can be added using batch online tools (or spreadsheet formula). I did this for 2019P152 using positions 24, 48 and 72 hours apart; to the extent calculated bearings change more than the track implies, the floe has rotated. Bearing, heading and course are a source of perpetual confusion but see:

https://www.movable-type.co.uk/scripts/latlong.html

There is no column for changes in drift speed (acceleration) but that is implicit as the slope of the tangent line to the speed graph (below). The one I looked at 2019 has a puzzling periodicity. Obviously if other 11 buoys don’t follow in parallel, they are diverging/converging and the ice in between is deforming.

2019P152
2019P155
2019P156

D Watkins, a grad student at Oregon State who studies ‘Arctic lower tropospheric temperature inversions in the CESM large ensemble’ deployed a second set of nine buoys (brand not provided) from the helicopter of the Akademik Federov.

2019P188  2019P196
2019P190  2019P198
2019P191  2019P200
2019P192  2019P203  2019P206

These buoys apparently do have an onboard accelerometer, though the column heading is "accelometer_variance ()" with units omitted but values ranging from 5 to 15. It’s not clear why the buoy should expect any waves in the next 8 months. I tracked down an explanation of sorts from NDBC not specific to this particular buoy:

Quote
How are spectral wave data derived from buoy motion measurements?
https://www.ndbc.noaa.gov/wave.shtml

NDBC-reported wave measurements are not directly measured by sensors on board the buoys. Instead, the accelerometers or inclinometers on board the buoys measure the heave acceleration or the vertical displacement of the buoy hull during the wave acquisition time. A Fast Fourier Transform (FFT) is applied to the data by the processor on board the buoy to transform the data from the temporal domain into the frequency domain. Note that the raw acceleration or displacement measurements are not transmitted shore-side. Response amplitude operator (RAO) processing is then performed on the transformed data to account for both hull and electronic noise. It is from this transformation that non-directional spectral wave measurements (i.e., wave energies with their associated frequencies) are derived. Along with the spectral energies, measurements such as significant wave height (WVHGT), average wave period (AVGPD), and dominant period (DOMPD) are also derived from the transformation.
« Last Edit: October 13, 2019, 01:55:03 PM by A-Team »

blumenkraft

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Re: MOSAiC news
« Reply #115 on: October 13, 2019, 05:12:40 AM »
The official trailer is quite heroic.  ;D

Refugees welcome

gandul

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Re: MOSAiC news
« Reply #116 on: October 13, 2019, 01:28:16 PM »
The official trailer is quite heroic.  ;D
It's just this Zimmer-esque soundtrack that is used for almost everything now, even for Trump Twitter videos.
I see science heroic but on the quiet side. But well OK.
No me lo trago

A-Team

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Re: MOSAiC news
« Reply #117 on: October 13, 2019, 05:54:10 PM »
Mosaic is posting the daily location radar in quasi-lagrangian coordinates, with the point position of the Polarstern and the North Pole determining the moving axis. In normal ship-based lagrangian coordinates, the bow-stern center line and main mast would determine the coordinate system (alternately some asymmetry axis on the floe to which the Polarstern is afixed). The difference is in how rotation is represented.

We are more used to eulerian coordinates in satellite archives where the graticule stays fixed. We went through this all before in the time of Ptolemy and Galilleo.

Whoever painted on the red lines and circle, over-writing the value of the most important pixels, seems not have centered them accurately on the ship which shows clearly as a bright white dot (all that metal reflecting Sentinel's beam back). Perhaps those circles reference a valid timestamp but one different from the S1 which would appear in its file name had it been correctly cited.

At any rate, I adjusted the six dates for which for which they archived S1 at higher resolution, so from Oct 7th to Oct 12th so far. As noted above, some of these are either mis-cropped or slightly rescaled from the others. The Polarstern tied on Oct 4th but those dates are missing (4-6 Oct).

We need to go back to the original files and do this over, right. I am not sure though that all of them are S1 as it does not seem that polarview carries them all at the needed resolution. If so that would mean a tedious navigation deep through the ESA server.

At any rate, despite the visual competition from the crazy graticule and red paint, it was possible to re-register six days of imagery. The four gifs below present the data at four levels of zoom. A lot could be said about leads opening and closing, scene deformation, rotation of the PS floe and so on. These run at 150 ms per frame; download and view frame by frame. I also prepared a single concatenate mp4 that has a better controller but am out of attachments here.

be cause

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Re: MOSAiC news
« Reply #118 on: October 13, 2019, 08:24:01 PM »
https://sabvabaa.nersc.no/  is taken from Andreas T's post on the abandoned Mosaic project thread and covers a similar journey a few years ago .. a good read . b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

A-Team

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Re: MOSAiC news
« Reply #119 on: October 13, 2019, 11:31:20 PM »
New snow buoy deployed by Mosaic on Oct 11th. 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).

Again, the manufacturer of the device are not provided; very likely the listed contact M Hoppmann of AWI can provide details. However the device is probably very similar to snow buoy 2014S12, deployed during Polarstern cruise PS82 though that one also measure internal ice temperature. Again, it is not the ice mass balance buoy that meereisportal keeps referencing (crossed out below).

https://doi.pangaea.de/10.1594/PANGAEA.875328

The database fields here can be readily integrated with the other 16 sea ice drift buoys in the growing array and its track displayed in GEP as before. Since all the buoys so far are reporting hourly on the hour, that can be used as the indexed field for a single composite flatfile db with just the essential lat,lon column + one additional parameter of choice.

This will allow individual tracks of the entire 17-buoy array to be displayed over bathymetry and coastline with either Voronoi or Delauney triangulation, with easy updating since the year is just getting started. This is just a paste into a kml template, not rocketry science.

https://data.meereisportal.de/gallery/index_new.php

time hourly on the hour   
latitude (deg) to 4 decimals
longitude (deg) to 4 decimals
distance_to_surface_1 (m)   
distance_to_surface_2 (m)   
distance_to_surface_3 (m)   
distance_to_surface_4 (m)   
barometric_pressure (hPa)   
temperature_air (degC)   
temperature_surface (degC)
« Last Edit: October 14, 2019, 12:00:17 AM by A-Team »

A-Team

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Re: MOSAiC news
« Reply #120 on: October 13, 2019, 11:44:09 PM »
Here are those additional floe tracking time series mention a couple of posts back. The first concatenates four levels of zoom into a movie with frame controller; the second presents 07-12 Oct 2019 data in eulerian coordinates that are better if overlays with other satellites are planned.

Here I used the .avi export option out of ImageJ and converted to mp4 with the free online tool:
https://cloudconvert.com/avi-to-mp4

The concept of a massively coupled buoy array is new and not fully implemented at meereisportal. The buoys are already experiencing glitches -- whether at the level of sensors, Iridium transmission or IT processing station at AWI I couldn't say -- that result in missing timestamps, eight in a row (4 hrs) for P152 and one for P188 (below).

These data gaps are not indicated by NaN or dashes as they should be; the csv files just skip the lines with no indication. Consequently, each person using the files has to run a separate detector for them (a new column subtracting consecutive time stamps sorted for anomalies).

The gaps then need to be filled in, most easily by linear interpolation from the lines above and below. If the csv isn't repaired, graphic representation of the buoy will be misleading and worse, be out of temporal synch forever more with locations of the other 16 buoys.

Some of buoys are reporting hourly, others twice hourly. If this seems excessive, it can be reduced to every 4, 8, 12, 24 hours by windowing with an appropriate fill-down averaging column followed by remainder (modular) arithmetic in the spreadsheet that consolidates all the individual buoy reports.

This master spreadsheet has one column for common time, lon and lat columns for track plotting, a column for displacement and a free column depending on what the particular buoy measures (air temp, snow depth etc). So far I have only put 4 of the 17 into a master. It starts 04 Oct 19 when the Polarstern first moored.

Then there is the matter of updating, say adding incoming data once a week. It's probably better to start from scratch rather than just appending because some of the data gaps might have been repaired and new buoys might have been deployed.

Meereisportal has not implemented the Polarstern itself as a buoy. While it is surely collected, I don't where that location data is posted in a compatible format.

Since the buoys are quite co-localized now, there may be grid regularization advantages in setting up companion files for virtual buoys (stable features on ice radar). This could only be done once a day, not hourly, and involves manual observation and recording.

The initial locations at deployment of the 17 buoys (at various dates) are shown in a broader context in the GE screenshot (orange polygon). The magenta and green circles show the largest possible free rotations of the ice pack without coming up against fixed land; green is restricted by the de Longa islands. The centers, called the poles of inaccessibility have been determined very accurately in recent papers.

Sort Active     Name       Long     Lat
 5   07.10.19   2019P188   135.99   84.71
10   05.10.19   2019P193   135.97   84.77
 7   07.10.19   2019P190   135.29   84.69
14   07.10.19   2019P200   135.06   85.00
15   07.10.19   2019P203   134.84   85.07
16   07.10.19   2019P206   134.48   84.97
13   07.10.19   2019P198   134.29   85.07
17   02.10.19   2019S92    134.24   84.78
12   07.10.19   2019P196   133.98   85.00
 6   05.10.19   2019P189   132.59   84.70
 9   07.10.19   2019P192   132.57   84.65
11   05.10.19   2019P194   132.07   84.71
 8   05.10.19   2019P191   131.71   84.66
 1   29.09.19   2019P152   125.86   84.24
 2   29.09.19   2019P155   125.23   83.78
 3   28.09.19   2019P156   121.26   82.09
 4   26.09.19   2019P157   119.25   81.39


GE line formatted:
134.29,85.07,0 134.84,85.07,0 133.98,85.00,0 135.06,85.00,0 134.48,84.97,0 134.24,84.78,0 135.97,84.77,0 132.07,84.71,0 135.99,84.71,0 132.59,84.70,0 135.29,84.69,0 131.71,84.66,0 132.57,84.65,0 125.86,84.24,0 125.23,83.78,0 121.26,82.09,0 119.25,81.39,0
« Last Edit: October 14, 2019, 04:16:28 PM by A-Team »

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Re: MOSAiC news
« Reply #121 on: October 15, 2019, 01:05:26 AM »
The first image breaks the latest radar image of the Polarstern's route into daily segments by using successively earlier dates (which have to be moved to align under their co-moving frame reporting).
Once again, we see that net travel over a week is far too long to resolve actual distance drifted by a factor of 3x here.

A junior scientist onboard twittered their initial mooring position in decimal minutes (!) as "84º04.582' 134º25.769' at 9:30 pm Friday boat time (!!)". I could not confirm that ship time used is UTC but would hope so. The PS may know its GPS position better than the buoys: 84.07637 134.42948 which suggests 1.1 m accuracy but that is not entirely clear.

ftp://ftpsrv2.awi.de/sea_ice/mosaic/jpg/large/mosaic_multisensor_map_2019-10-13_hr_NoOverlay.jpg

If the adjacent ice pack were moving as a rigid non-deforming block, the buoys would all change speeds in concert. They don't quite (slide show, 4 PRIC buoys).

Esther Horvath has been taking some great photos from the PS. The ice thickness looks barely able to support some of the heavy gear that has to be set up on the ice, such as the 'Ocean City' electric hub.

https://follow.mosaic-expedition.org has high resolution photos on the side.
https://mosaic.colorado.edu/blogs has good posts from the Polarstern
« Last Edit: October 15, 2019, 03:26:12 AM by A-Team »

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Re: MOSAiC news
« Reply #122 on: October 15, 2019, 05:16:04 PM »
Update on the position of the Polarstern and the ice immediately around it, eight days to 14 Oct 2019. The selected floe continues to drift the wrong way (south towards Siberia). The icepack edge has scarcely advanced towards Russia or Alaska in recent days though ii is almost all thickened beyond the 0.5m sensor cutoff on SMOS.

The floe has not rotated so far despite a multi-day ice cyclone sweeping up from Banks Island (green over-tint, lower left OsiSaf). 

Although ice movement is strictly wind-driven (subject to boundary conditions and internal cohesion), it rarely corresponds to anything seen in GFS near-surface winds at nullschool. We lost daily coverage of ECMWF in the forked windy.com code when Arctic view was killed for lack of sufficient clicks. 

I sincerely doubt that GFS will assimilate data from Mosaic buoys and Polarstern any time soon though that would improve its initializations and ever-changing near-term forecasts.

Only spotty information has been released to date about the selected floe's ice thickness, snow cover, lead/ridge/keel structure and historic provenance despite many EMBird transects flown. S1 radar shows north and south regions of the floe as quite dark (poor return of impinging radar beam) with a better reflecting (whiter) speckled east-west stripe.

This can tentatively be interpreted in terms of near-surface dielectric: dark areas are older ice that are farther along in extruding brine pockets that form during freezing, lighter areas are newer, speckled surface arise from fusion of two floes via freeze-over of intervening sea water and collisional compression into ridges and jumbles. The ice is so thin though that salt left by over-washing waves sometime in the past has affected the surface.

If so, the Polarstern is moored to the weakest part of the floe. However I don't expect shearing here because a number of old leads can be seen opening and closing in the near vicinity; these will accommodate regional ice strain.

The fourth image, taken from Uniq at #82, shows the Polarstern's floe without all the disruptive overlays. I made some very slight improvements in image quality by linear contrast spreading, weak adaptive contrast enhancement and unsharp mask. Two off-the-shelf indexed color palettes provide a start on ice classification based on radar reflectance (residual near-surface polarity).

It is possible, with a big handful of €€€s, to order up much higher resolution SAR imagery of the floe. Possibly that new company would do it gratis for the press. It's too late to order visible as the cloud-free sunlit window closed Sept 24th.

What is causing these wild swings in overall light/dark radar contrast in successive days at the same spot? Maybe S1A vs S1B or ascending vs descending orbits. Hard to say, they don't provide image identifying numbers.

The buoy data is like that too, referenced with shipboard chatter. Buoys are required to have a unique IMEI to transmit wireless data; that identifier is their real name. The IMEI then is tied 1:1 with 2019P155 etc so informally P155 (as other years are not involved).
« Last Edit: October 15, 2019, 07:09:37 PM by A-Team »

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Re: MOSAiC news
« Reply #123 on: October 15, 2019, 09:53:07 PM »
An update on the meerisportal buoys on macid's post upthread, tinkering with the code a little enables us to zoom in on the 12 buoys closest to the polarstern location. Still not sure which is the most flexible buoy analysis tool.

polarstern temperatures from sailwx

a crop of today's polarview jp2, linear contrast. 2 very bright radar reflections to the rhs. A new part of the mosaic installation?
« Last Edit: October 15, 2019, 10:26:48 PM by uniquorn »

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Re: MOSAiC news
« Reply #124 on: October 16, 2019, 12:35:57 AM »
Quote
tinkering with the code a little enables us to zoom in on the 12 buoys
Very nice! Most excellent progress on a viable multi-buoy display. It maps polar coordinates to cartesian, similar to mapping the earth ellipsoid to a mercator cylinder rolled out to a flat tangent plane. This will work quite well as long as the buoys are clustered near each other. As the year goes on, they will disperse all over the Eurasian AO and distortion will increase unacceptably.

I looked at putting another nice ice graphic by E Horvath of the Polarstern parked at its floe underneath the sprites ... so-so outcome to date.

Buoy repositories are popping up all over, which is great for data availability. These are being structured as relational databases rather than flat-file; for example Meereisportal is putting auxillary flatfile dbs in mouse-over notes.

Any relational db can be accommodated in a flatfile like excel. However that is very inefficient and a great many cells will be empty. Relational db are constructed relative to a master key (buoy indexing file) which in this case is the mandatory IMEI mobile device number.

That is the counterpart to the latin binomial of a plant, eg Dryas octopetala. There, just like with the buoys, divergent common names are used mountain avens, eightpetal mountain-avens, white dryas, and white dryad. (And that's just english.)

What I’ve seen so far is not going to scale for coordinated analysis of say six dozen buoys posting 5-6 columns of data 48 times a day over a year (7,568,640 cells).

In my view, a front end is needed that allows the data set to be sensibly queried. For example, someone might want only buoy data over a specific time frame, from only buoys within a specified initial radius of the Polarstern that have both air temperature column and snow thickness with no more than 2% NaN gaps.

For this, a natural choice would be (open source, highly developed, widely used) MySQL rather than proprietary software or ad hoc code. While this could/should have been up and running using proxy data given eight years of Mosaic planning, it wasn’t. These sites are not going to restructure mid-season but rather dig themselves in deeper.

Quote
2 very bright radar reflections to the rhs. A new part of the mosaic installation?
Do we have lat/lon for them? They may not be buoys but rather passive metal containers/reflectors like the 'Ocean City' transformer. Alternatively, they could be rfi (radio frequency interference) from active emitters that sometimes plague Smos and AMSR2 (despite reserved frequencies).

In the 122-page planning document, it's noted that all electrnic devices on board must be a signature registered with the ship because with 300 tons of equipment, some rfi is only to be expected initially. Email to 50 kb text is allowed to anyone appropriate on the ship; no hefty graphics.

@zlabe is posting very useful negative NAO anomaly graphics bimonthly which are something Mosaic needs to keep an eye on if they want transpolar drift. Not that there's any way to flip negative to positive. I've attached the daily pattern since mid-March.
« Last Edit: October 16, 2019, 01:24:30 AM by A-Team »

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Re: MOSAiC news
« Reply #125 on: October 16, 2019, 07:42:23 PM »
Today's polarview image, this time showing the jpg with graticule (no contrast change),
The longitude lines are 132 and 128E
Maybe too much movement from yesterday in the 3rd reflection for a tethered object.
edit: obviously it was AF that moved, see gif below, click to run, click all images for full resolution.
more edit:
 jp2 saved as png with linear contrast and a smaller crop jp2@200% bicubic>png  (honester ;) ).
struggled a bit with the gimp contrast but this should be linear
« Last Edit: October 17, 2019, 12:29:14 AM by uniquorn »

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Re: MOSAiC news
« Reply #126 on: October 16, 2019, 10:15:09 PM »
Quote
16-bit p2 saved as png with linear contrast and the same jp2>png default (honest
Wie, bitte? On these large 16 bit jp2 that open as 16 bit in current versions of Gimp but not ImageJ, the contrast and resizing tools will work for initial steps at the 16 bit level. This provides a huge advance in opportunities over 8-bit because the pixel value histogram, which is initially a cookie-cutter gaussian distribution, doesn't bin up as contrast tools operate, introducing visually apparent round-off errors. (The 16-bit also has to round calcs but the error is out in weedy decimals and is discarded later.)

Here the jp2 might open as color but it is really just one-channel grayscale, like an Ascat gif. Those i put into 8-bit gray, then bump in 16-bit and sometimes 32-bit before running re-sizing and contrast tools. However it's ultimately necessary to drop back down to 8-bit when pasting back and forth with Gimp or posting to forum.

We very much want to get the best possible radar image of the floe and surrounding area, optimally enlarged 2-3x with bicubic while still in 16-bit, because yesterday the Helmholz blog posted two very important high resolution images of floes made with via sled and helicopter instruments.

The Sentinel images come as 'Greenland down' so need a 180º rotation to get north up to match. This is a integer matrix transform which does not recompute splines and so has zero effect on resolution at any bit depth.

The Polarstern also has access to TerraSAR-X (DLR) which is one of these crazy public-private partnerships where the public pays once but pays again to see. Canada likes this too; only oil and mining companies can afford the imagery.

Just asking for a friend: Do CA and DE pay for all the multi-billions of satellite freebies that NASA puts online? Do they pay for all the multi-billions of medical genome data the US gives away? Do they pay for use of GFS; do we pay for ECMWF built off our satellites?

One of the prime objectives of Mosaic -- since a ship cannot always be out there -- is to improve interpretation of daily satellite imagery. Here we have mildly dated RGB and VIIRS band 31 images of the selected floe (ausgewählten Scholle) but daily tag-along Sentinel radar for the coming twelve months.

The Mosaic time posted a very interesting graphic of GEM-2 EM ice thickness over a high resolution radar of a floe they investigated early on but didn't choose. The date, scene ID number and grid scale aren't provided nor is the latitude (~85º?) though it lies along 137ºE. Again, better to provide layers so people can see what is buried under the opaque swath lines.

https://blogs.helmholtz.de/polarstern/en/2019/10/mapping-floes
On board 10 Oct 2019 by Stefan Hendricks and team:

Quote
…  to measure each floe’s thickness we used the Polarstern sled's built-in electromagnetic ice-thickness sensor. By combining our findings onsite with the radar images from the satellites, we arrived at an overview of the ice situation in the region. Lighter areas on radar are associated with rougher surfaces characteristic of thicker ice; darker radar returns with thinner smoother ice.

The other tool is an airborne laser scanner (ALS) which can detect fine-scale changes in surface height below the helicopter. The sensor has a 300 m swath. The floe is ~2500 x 3500 sq meters.

What we found: the vast majority of the floes surveyed consisted of very thin (30 – 70 cm) sea ice and had meltwater ponds (Schmelztümpeln) that had since frozen over, a clear indicator of intensive melting in the summer, on much of their surface area. Floes of this type can easily break apart or be pushed together, which makes long-term, continuous monitoring and measuring work highly problematic.

Indeed, in the past few days, heavy winds have produced a number of cracks in the ice of our floe, as a result of which our map is no longer entirely accurate. It’s precisely events like this one that we plan to spend the next year investigating. [[paraphrased]]
The first map shows the Polarstern moored on its starboard side to the floe. The bow is used as center of a polar coordinate graticule and extends out as the 0 of 12 angles set out CCW like wristwatch hours. Latitude circles are set out every 250 m out to about 3 km. North is not indicated but apparently straight up; magnetic north is really problematic at these latitudes given rapid wandering of that pole and erratic drift of the floe.

The color scheme is qualitative: light blue for thin ice, dark blue for thicker and white for elevated ridges and standing ice blocks. Snow depth is not shown. No color scale is provided. This is odd because the ALS is a precision laser. It's not clear whether ALS data has been combined with the thickness sled or is just being used as a freeboard detector.

We'll be referring to this camp map and ice thickness a lot: the direct link to the 3112 x 3691 image is below. I've scaled it down by 3/8 for the forum (to 1140 x 1400, needs click to see) and added a small Sentinel floe scene (to be replace soon by a Uniq jp2.)

https://blogs.helmholtz.de/polarstern/wp-content/uploads/sites/16/2019/10/20191014_MOSAiCLeg1_Schollenkartierung-abb4-ALSFloeMap.jpg
« Last Edit: October 16, 2019, 10:33:32 PM by A-Team »

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Re: MOSAiC news
« Reply #127 on: October 16, 2019, 10:45:02 PM »
Whoa ... 600 of them acquiring all this data, a handful of people here trying to assimilate it?

Eight new buoys. These are CTD types: instrumented wires hanging down holes drilled in the ice to 100 m to record temperature, salinity, conductivity, and water pressure at four depths (rather than continuously like a profiler motoring sensors up and down a wire). Not much on surface except air temperature and nrt GPS. These are not ice mass balance profilers as they do not measure thickness or temperature of the ice.

These were basically deployed along 85ºN at various longitudes 131-137ºE so make for a very good set of differential drift detectors. We are up to 25 new buoys with GPS plus the PS.

This is really short-sighted of Mosaic not to name these systematically (who thought of 1,2,...8?) Hopefully Meereisportal will correct it but so far they have not. They should be categorized as Ice Beacons, that is 2019B01 etc.The buoys do have IMEI identifiers. No one is listed as contact. They were deployed from 07-11 Oct 19 on but data first surfaced on Oct 15th.

The slow slide show below shows the results these buoys collected so far.

 time interval: 10 minutes
 latitude longitude (decimal degrees to 1:10,000)
 buoy submerged (yes/no)
 air temperature_at_surface (degC to tenth degree)
 conductivity, salinity, pressure and water temperature at   10m (S/m, psu, hPa)
 conductivity, salinity, pressure and water temperature at   20m (S/m, psu, hPa)
 conductivity, salinity, pressure and water temperature at   50m (S/m, psu, hPa)*
 conductivity, salinity, pressure and water temperature at   75m (S/m, psu, hPa)
 conductivity, salinity, pressure and water temperature at 100m (S/m, psu, hPa)

 S/m: sieverts per meter
 *salinity not reporting

The graphic below has an inset postage stamp of google earth waypoints for the Polarstern made at AWi. The numbers can be scrapped out of text-view from the following snippet of kml:

https://www.awi.de/fileadmin/user_upload/MET/PolarsternCoursePlot/polarstern.kmz

<coordinates>
               133.6,84.8,0 133.6,84.8,0 133.7,84.8,0 133.7,84.8,0 133.7,84.8,0 133.8,84.8,0 133.8,84.8,0 133.8,84.8,0 133.9,84.8,0 134,84.8,0 134.1,84.8,0 134.1,84.8,0 134.1,84.8,0 134.2,84.8,0 134.2,84.8,0 134.2,84.8,0 134.2,84.8,0 134.2,84.8,0 134.3,84.8,0 134.3,84.8,0 134.3,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.4,84.8,0 134.5,84.8,0 134.5,84.8,0 134.5,84.8,0 134.5,84.8,0 134.5,84.8,0 134.6,84.8,0 134.6,84.8,0 134.6,84.8,0 134.6,84.8,0 134.6,84.8,0 134.7,84.8,0 134.7,84.8,0 134.7,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.8,84.8,0 134.9,84.8,0
            </coordinates>
The right hand side shows a crop of the left hand legend corner of all the mosaic multisensor maps. It shows the ship lat/lon position times are quite erratic relative to (not-provided) radar timestamps. This may explain why the red overlay circles are such a clumsy fit to the actual white pixels of the ship -- different times. It's not clear whether the wavy intermediate transparent red track between my green squares (the actual ship displacement on the day stated) follows actual hourly ship GPS waypoints or is just creatively hand-drawn.

The final graphic illustrates the latest meteorology collected on the Polarstern, something that it has been doing for the last 25 years. This data is sent in immediately to be assimilated for ECMWF forecast initialization (and later re-analysis).

The wind angle graphic is not so easy to read but they provide that digitally as well. Mosaic has a plan for 5-day ice motion prediction (SPIDX?) so real near-surface data will be important to that.

https://www.awi.de/fileadmin/user_upload/MET/PolarsternCoursePlot/psobsedat.html
Last update: Wed Oct 16 11:00:01 UTC 2019
Near real time 1-hourly routine synoptic observations
« Last Edit: October 16, 2019, 11:29:13 PM by A-Team »

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Re: MOSAiC news
« Reply #128 on: October 16, 2019, 11:42:23 PM »
Meereisportal just uploaded a whole new batch of floes while I was typing up the post above. There are now 35 deployed.They are playing catch-up, these new ones were set out some time ago.

Their table is quite good, though it could use a couple of columns for latest positions as well as sort options. However the html is clean and it drops right into excel. The attached csv file shows the buoys sorted by name, northernmost latitude of deployment, and reverse chronological deployment order. Be good to add the IMEI and whatever UW buoy center has about them, 2nd link.

They do encourage questions, the Helmholtz blog allows replies, the twitter sites have threads and so on. Below I started on social media translations and site names of the ice camp:

Fortress   Festung
Courtyard   Hof
Outer Wall   Außenwand
Sculpture  Garden   Skulpturengarten
Gatewy   Tor
South Beach   Süd Strand
refrozen ice lead   gefrorene Eisriss?
melt  pond   Schmelztümpeln
Area 3 logistics    Bereich drei

omg   omG
IMO   mMn
RSVP   uAwg
CUL8R   bd
idk   kA

data.meereisportal.de/gallery/index_new.php
http://iabp.apl.washington.edu/TABLES/ArcticTable.php

Blue: discussed immediately above
Purple: discussed earlier
Red: need a look

2019O1   84.61   130.65   05.10.19
2019O2   84.56   134.77   07.10.19
2019O3   84.75   136.59   07.10.19
2019O4   84.85   133.76   08.10.19
2019O5   84.92   136.24   09.10.19
2019O6   84.96   130.97   10.10.19
2019O7   84.63   133.60   11.10.19
2019O8   84.86   132.23   11.10.19

2019P152   84.15   124.63   29.09.19
2019P155   83.62   123.58   29.09.19
2019P156   81.85   118.45   28.09.19
2019P157   81.08   116.74   26.09.19
2019P188   84.65   134.41   07.10.19
2019P189   84.64   131.07   05.10.19
2019P190   84.64   133.72   07.10.19
2019P191   84.60   130.21   05.10.19
2019P192   84.59   131.05   07.10.19
2019P193   84.72   134.38   05.10.19
2019P194   84.65   130.56   05.10.19
2019P196   84.94   132.49   07.10.19
2019P198   85.01   132.83   07.10.19
2019P200   84.94   133.58   07.10.19
2019P203   85.01   133.38   07.10.19
2019P206   84.91   132.95   07.10.19

2019S79   84.56   135.50   07.10.19
2019S80   84.86   134.44   07.10.19
2019S81   84.76   137.21   07.10.19
2019S86   84.96   131.59   07.10.19
2019S87   84.92   136.82   07.10.19

2019S92   84.69   132.94   07.10.19
2019S93   84.68   134.74   07.10.19
2019S94   84.97   133.95   07.10.19
2019S95   84.63   134.32   07.10.19
2019S96   84.78   131.82   07.10.19
« Last Edit: October 17, 2019, 12:21:47 AM by A-Team »

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Re: MOSAiC news
« Reply #129 on: October 17, 2019, 12:49:15 AM »
Plenty to do tomorrow then. Updated my previous post using gimp 2.10.12. Will look through polarview images to see if any have better definition. Here is 400% scale of image above in gimp, saved to png -> imageJ, further linear contrast, adaptive contrast then unsharp mask. It retains a few more features than the standard jpg.

http://iabp.apl.washington.edu/WebData/  is easier access to iabp .dat files using the 15 digit id.
« Last Edit: October 17, 2019, 01:03:32 AM by uniquorn »

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Re: MOSAiC news
« Reply #130 on: October 17, 2019, 02:01:00 PM »
Below I update the daily segments of Polarstern drift to 16 Oct 2019, made an overlay of the drift track on Smos of the same date (where it barely shows, even somewhat exaggerated), and took your best S1B of Oct 6th above and enhanced/enlarged it to fit over the Ice Camp which the S1 radar lacks the resolution to do really. The radar needs a 180º rotation to fit the ship's convention.

That is, the Ice Camp original is posted 975 pixels for 1000 m (did they intend 1:1?) whereas the
recent mosaic multisensor maps have 3797 pixels for 1º of latitude (111.111 km) which is 29.3 pixels per meter. Thus the Ice Camp has a better scale by 30:1

Nonetheless, the fit is quite informative in terms of helping to interpret radar over the wider scene. I am still of the view that the thicker ice in the Mosaic floe is a mashup of two thinner floes, either collision or over-riding. It is FYI that has barely graduated to SYI. The floes all around it are 70-90 cm. The year of Ascat rules out an MYI drifting into this area.

We did find the floe on Worldview for a few days in late Sept (somewhere above). At its best resolution, 9 pixels per 1000 m, even less can be expected for the overlay. Hopefully the Polarstern took visible imagery in early October.

Low sun angle can be extremely effective showing quantitative topographic relief as we've seen at Jakobshavn. If not, they might scan the Polarstern's very powerful searchlights across the scene while a helicopter records from above.

For people wishing to do the daily (weekly?) download of all the Mosaic buoys, simply use a web browser utility that can open a list of urls and save image contents. I obtained this by drilling into the open file system at meereisportal and copying/sorting the buoy directory. The url shown is an example; add the front part to the buoy name + IMEI list. Note 2019S88 is listed but its location isn't relevant.

The timestamp, lat, lon, speed columns are invariably the first four so if that is all you want to plot drifts, there may be some simple way of opening all the downloads in excel as a stack and deleting all the rest. It would be better if the buoys were in reverse-chron order as that would synch the rows of buoys that had different deployment dates. Still, some are on the hour, others on the half hour, skipped times not indicated with empty rows.

Note the confusion presented by 2019O1-O8. These have a zero and a capital 'O' for buoy type. (However Meereis does not have an explanation for this category in its pop-up key.

https://data.meereisportal.de/download/buoys/2019O2_300234068160720_proc.csv

2019O1_300234068066320_proc.csv
2019O2_300234068160720_proc.csv
2019O3_300234068164710_proc.csv
2019O4_300234068166760_proc.csv
2019O5_300234068169760_proc.csv
2019O6_300234068514740_proc.csv
2019O7_300234068519770_proc.csv
2019O8_300234068713430_proc.csv
2019P16_300234062881930_proc.csv
2019P22_300234062887920_proc.csv
2019P152_300234068218450_proc.csv
2019P155_300234068316210_proc.csv
2019P156_300234068312200_proc.csv
2019P157_300234068312210_proc.csv
2019P188_300234068121990_proc.csv
2019P189_300234068221000_proc.csv
2019P190_300234068220020_proc.csv
2019P191_300234068123990_proc.csv
2019P192_300234068129990_proc.csv
2019P193_300234068125990_proc.csv
2019P194_300234068222000_proc.csv
2019P196_300234068226020_proc.csv
2019P198_300234068910810_proc.csv
2019P200_300234068910590_proc.csv
2019P203_300234068915790_proc.csv
2019P206_300234068917830_proc.csv
2019S79_300234066344810_proc.csv
2019S80_300234066346540_proc.csv
2019S81_300234066444880_proc.csv
2019S86_300234066995900_proc.csv
2019S87_300234067009210_proc.csv
2019S92_300234066080170_proc.csv
2019S93_300234066081140_proc.csv
2019S94_300234066081170_proc.csv
2019S95_300234066081180_proc.csv
2019S96_300234066083120_proc.csv
« Last Edit: October 17, 2019, 10:13:46 PM by A-Team »

uniquorn

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Re: MOSAiC news
« Reply #131 on: October 17, 2019, 04:50:58 PM »
A quick overview of mosaic Pbuoy drift before moving on to others.
« Last Edit: October 17, 2019, 05:01:45 PM by uniquorn »

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Re: MOSAiC news
« Reply #132 on: October 17, 2019, 06:34:40 PM »
WOW, you can see the tides!  :o
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Re: MOSAiC news
« Reply #133 on: October 17, 2019, 07:13:57 PM »
 Looks like it.
Here showing the Sbuoys drift and air temperature. Will have to work out how to show 'distance to surface' 1-4 later.
Anomalous movement on the last buoy at the end. Have to work out labelling also.

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Re: MOSAiC news
« Reply #134 on: October 17, 2019, 07:33:08 PM »
You and A-Team are doing an amazing job visualizing this stuff. Thanks so much for that.

I hope the folks on the Polarstern follow your work. Maybe get ideas from you? Maybe give us additional data to work on?

One can dream, right? ;)
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Re: MOSAiC news
« Reply #135 on: October 17, 2019, 09:00:43 PM »
Thanks also to macid for the original coding. I am just script oldie.
edit: changed animation, temperature at 100m was more interesting. I wonder what is going on down there?
All 36 meerisportal buoys, for the record. Click to run.
« Last Edit: October 17, 2019, 10:32:32 PM by uniquorn »

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Re: MOSAiC news
« Reply #136 on: October 17, 2019, 10:40:01 PM »
Grrr... reconciling Meereisportal with UW's IADB global buoy database turns up 73 69 buoys associated with Mosaic. They are all in the 85/136º neighborhood and still actively reporting October 15-17 (except for 2019P16 which last reported on the 11th).

IADB does not allow collection of urls to the data directory; the links on their site are fast but lead to some mumbo jumbo and an onClick .dat file (same as .csv)
 
http://iabp.apl.washington.edu/maps_daily_table.html
<a href="#BumBuoys" onClick="popData(300234010077180);"

The confusion presented by 2019O1-O8: these are not just badly numbered 1-8; they have a zero and a badly chosen capital 'O' for buoy type. However Meereis does not have an explanation for this buoy type in their pop-up key. IADP calls them CTD type which fits their data content.

Tides in the middle of the ocean go up and down, merely 30-50 cm at the locations considered. GPS measures sideways. Tidal currents go sideways but mostly near islands or mainland.

Meanwhile inertial waves (wind-induced, coriolis restoring force) have a 12 hr period whereas tides are more like 12:50. (One of the authors below was my roommate in grad school!). There could also be periodic systemic errors having to do with time of day and the buoys position relative to the GPS satellite constellation

Near-Inertial Wave Propagation in the Western Arctic
R Pinkel
https://journals.ametsoc.org/doi/full/10.1175/JPO2715.1

Observations of internal wave generation in the seasonally ice-free Arctic
L Rainville and RA Woodgate
http://shoni2.princeton.edu/ftp/lyo/journals/RainvilleWoodgate-IWavesIceFreeArctic-GRL2009.pdf

Dynamics of the Changing Near-Inertial Internal Wave Field in the Arctic Ocean
HV.Dosser and L Rainville
https://journals.ametsoc.org/doi/full/10.1175/JPO-D-15-0056.1

Revisiting internal waves and mixing in the Arctic Ocean
JD Guthrie  JH Morison  I Fer
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/jgrc.20294

Year-round observations of sea-ice drift and near-inertial internal waves in the Northwind Abyssal Plain, Arctic Ocean
Y Kawaguchi et al
https://www.sciencedirect.com/science/article/abs/pii/S1873965218301087

Here are the latest lon,lat coordinates for the 69 buoys in Goog Earth format.

132.11,84.684,0 133.9046,84.6754,0 133.2518,84.9642,0 133.4718,84.6228,0 132.2082,84.7568,0 133.646,84.85,0 130.8486,84.957,0 136.1034,84.9136,0 134.500,84.9796,0 130.35,84.61,0 134.44,84.55,0 136.26,84.74,0 133.48,84.85,0 135.93,84.91,0 130.71,84.96,0 133.29,84.62,0 131.95,84.85,0 131.59,85.05,0 133.94,84.53,0 136.40,84.94,0 135.27,84.72,0 136.89,84.70,0 132.23,84.66,0 135.13,84.79,0 135.39,84.96,0 134.74,84.94,0 131.43,84.83,0 133.68,84.68,0 133.25,84.69,0 131.54,84.79,0 133.16,84.71,0 132.20,84.64,0 132.63,84.72,0 131.93,84.73,0 132.84,84.79,0 132.44,84.69,0 131.55,84.70,0 134.09,84.65,0 129.90,84.60,0 134.07,84.71,0 130.74,84.58,0 133.39,84.63,0 130.76,84.64,0 130.25,84.65,0 132.20,84.94,0 133.28,84.94,0 132.55,85.00,0 133.09,85.01,0 132.66,84.91,0 133.75,84.97,0 132.69,84.69,0 134.80,84.68,0 130.72,84.96,0 131.95,84.68,0 133.76,84.67,0 133.75,84.67,0 134.45,84.55,0 136.27,84.74,0 132.83,84.76,0 132.76,84.76,0 123.98,84.15,0 117.69,81.75,0 115.96,80.96,0 122.91,83.59,0 132.05,84.75,0 124.31,85.85,0 132.15,84.41,0 116.92,85.51,0
« Last Edit: October 18, 2019, 12:46:22 AM by A-Team »

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Re: MOSAiC news
« Reply #137 on: October 18, 2019, 01:45:41 PM »
An extensional crack was reported yesterday out as the meteorological tower was being installed in Met City. The fissure has since widened to 5 cm; the length has not been reported. Np equipment has been lost or damaged.

No map has been provided showing position of the crack relative to the radar image, conceptual camp layout or high resolution Ice Camp lidar map.

Met City was not planned to be located straight out (ie perpendicular) from the ship but rather at 45º CCW. This would put it at about 2hr on the Ice Camp map above, in or below the Fortress Area.

We need more information before the crack can be related to regional ice pack motion but so far no shearing has been seen, the floe has experienced an extensional failure, probably because "it couldn't keep up" with the rest of the regional ice pack as it moved zonally towards the islands of SZ under the influence of persistent easterly winds.

Since the freeboard is only four inches or so, someone could stick their hand in the crack and touch sea water. However it will freeze very rapidly sandwiched between two slabs of cold ice, air temperatures being irrelevant. (This happens in mountaineering when someone falls into a crevasse and is why two rope teams are imperative.)

What caused the crack?

(1) Ship photos show a full moon. That will bring out the tidal conspiracists in force. How this could come into play 500 km from land in 4000 m water at extreme polar latitude needs a quantitative exposition, in particular prediction of the crack's orientation of the crack which I expect to be more or less perpendicular to wind direction.

(2) What happens out there is floes differ greatly (ridges, edges) in the extent to which the wind can take a hold (friction). This results in a very uneven tensile stress that is not offset yet by compression of the ice pack against land. Pushing on nearby water that envelopes the periphery -- or even on sub-100% concentration ice -- is like pushing on a string. These forces are maybe 3-4 orders of magnitude more significant than tidal.

(3) The ship itself induced the crack. It is in effect a very tall pressure ridge that catches a lot of wind. It created a long wide lead of broken ice coming in -- the ship has a beam of 27 m.

The 'gale force' winds reported could have torqued the ship against the ice pack, leveraging crack formation. When the Akademic Fedorov was along side, considerable collateral impacts were seen in the adjacent still-fragile ice.

Planning documents show Mosaic is very well aware of "observer effect" issues presented by the ship itself, resupply vessels, and bunker fuel exhaust and has mitigation plans for all of them. Events like pressure ridge and lead formation are not at all unusual -- and studying them in situ is one of the reasons the PS is out there.

(4) Waves and strong swells developing over a long reach can indeed penetrate hundreds of kms into an ice pack and be highly disruptive. However that can be ruled out in this instance, even though the Polarstern did report a day or two of gales.

(5) Ocean currents can be ruled out: there are no surface here, other than what is induced by keels of ice blown by the wind. Even if independent near-surface currents did exist, they would just carry floes along rather than stress them. If at an angle to wind stress, floes would be sheared.

The twitter sites and blogs have no had spontaneous coverage to date; they are typically multiple days behind events and are largely communication promotions pitched at major media or education.

This crack was accompanied by a major oddity in the mosaic_multisensor daily drift which shows the Polarstern as having left the floe. However it appears that they were not able to obtain a fresh Sentinel image and simply re-used the one from yesterday (see identity in comparison below).

The Polarstern has not left because of the crack incident and is still moored to the floe which regionally is drifting up against Severnaya Zemlya.

https://epic.awi.de/id/eprint/50082/1/Expeditionsprogramm_PS122.pdf page 13 map
« Last Edit: October 20, 2019, 03:32:46 AM by A-Team »

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Re: MOSAiC news
« Reply #138 on: October 18, 2019, 03:47:49 PM »
Today's polarview jp2->png, inverted. PS still moored. Default size showing surrounding area leads and 300% with standard unsharp mask.
Interesting that the leads are largely east/west

Where did the terrasar image come from?
https://earth.esa.int/web/eoportal/satellite-missions/t/terrasar-x

edit: added a guestimate overlay of fortress image above. Those leads look quite imposing.
« Last Edit: October 18, 2019, 04:36:08 PM by uniquorn »

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Re: MOSAiC news
« Reply #139 on: October 18, 2019, 07:39:23 PM »
Quote
Why can't we the funding public get access to terraSAR imagery?
It is being used quite a bit now at Neumayer Station in Antarctica. Provides great imagery ... though we are looking for ultra-high resolution at one spot in the Arctic Ocean; orbital coverage may have to be requested.

I found that image on the blog of R Moore, who is part of the @MOSAiCArctic field school. It did not enlarge on a click and but does  not represent the full quality available. It is 1024 x 795 and said copyrighted, though under non-commercial Fair Use Doctrine, it can be freely distributed especially if trivial changes like 180º inversion are made (new art).

The blog posting predated selection of the floe. She did not know/say that this was The Floe, that is my interpretation. As usual, no identification numbers were provided with the image so we wouldn't know what to ask for. It is better to embed ID numbers in the image or include them in the file name so they can't get separated (as in EXIF metadata).

Exif direct-to-url yielded:

Pixels Per Unit X: 2835
Pixels Per Unit Y: 2835
Pixel Units: Meters
Modify Date: 2019:10:15 01

Here that was ominously satImage_smallsize.png which could mean cropped or dumbed down in resolution or both. Sounds like it was resized down from an original 2835 x 2835 but by whom? The floe is about 100 pixels high as downloaded; in real life it is ~3500 m in this dimension. The exif meters/pxl then makes no sense.

I did not get anywhere walking back the directory to a folder that might contain a full size version, just 403's forbidden. Not sure why it is hosted at CIRES Colorado when Moore is a grad student in applied math at Utah, on the AF for six weeks. At any rate, I wrote away for the original file.

https://mosaic.colorado.edu/sites/default/files/inline-images/satImage_smallsize.png

ttps://mosaic.colorado.edu/news/remote-sensing-and-buoy-simulations-important-tools-mosaic
https://mosaic.colorado.edu/blogs
https://twitter.com/AWI_Media

Quote
Interesting that the leads are largely east/west. Those leads look quite imposing.
That is a typical shearing pattern seen in brittle material failures. It extends some 20 multiples of the floe's width in the png posted above which is ~50 km. There is some hint that it has forked around the (thicker) selected floe. Today was a two-fer on S1B: the PS floe was caught at two times an hour and 38 minutes apart (below, green dot is Polarstern).

We need to map the opening and closing of leads over the last month, easy given a co-registered archive. Both Gimp and ImageJ are loaded with edge detectors, which is run on your image below.

Leads can open and close up overnight to the point of unrecognizability. Pressure ridges ... not sure they can be seen. Might be lighter lineations due to roughness on the scale of Sentinel-1AB which operate at 5.404 gigahertz, meaning surface roughness at the order of the 5.5 cm wavelength.

Incredibly close call with those big leads opening but they could have relieved a lot of regional ice stress. They also could have sent a lot of difficult-to-replace and mission-critical equipment down to a watery grave. (As happened on two occasions to the hovercraft party.) Or split the legs on the Met tower if 5 m to .the left. It is interesting how much ice noise they report even frozen on the floe.

Update: looks like those big leads arose as single CW torquing failure during an "attempted rotation". The wind shifted. I'll add the whole time series in a bit ... taking screenshots off https://www.polarview.aq/arctic saves trying to locate the Polarstern on a huge downloads.
« Last Edit: October 19, 2019, 12:28:56 AM by A-Team »

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Re: MOSAiC news
« Reply #140 on: October 18, 2019, 09:54:16 PM »
Back to the buoys. Here are the drift/delivery paths of 64 iabp buoys near the Mosaic area. There are 3 more, I think, with short identifiers and a slightly different format, not shown. Some have occasional -ve entries. At some point the id number should be related to buoy type.
Current list is attached as txt file.
added meerisportal list.
« Last Edit: October 19, 2019, 01:12:29 AM by uniquorn »

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Re: MOSAiC news
« Reply #141 on: October 19, 2019, 01:54:32 AM »
The weather forecasts are becoming increasingly interesting for anything that may be Fram bound . The floe will be going with the flow at quite a pace and may be seriously challenged by wind and wave if forecasts verify . b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

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Re: MOSAiC news
« Reply #142 on: October 19, 2019, 09:05:19 PM »
Quote
floe may be seriously challenged by wind and wave if forecasts verify
Right. It is the unevenness in the stress applied by the wind to the floe and vicinity that wrenches the ice around. It would not be disruptive to the Polarstern's floe if the entire ice pack were rotating uniformly unconstrained by CAA land, but it isn't.

It has not been possible so far to predict ice motion from weather forecasts; one of the goals of Mosaic is a five-day ice forecast.

The small crack that went through camp the other day was part of a much larger and potentially more damaging event. While leads can open any time of the year, the ice today has not set up enough to resist deformation.

The Polarstern did not get the worst of it in the 16-19 October event but a lot of the Mosaic experiments in the Deployed Camp will have to be moved (or reconsidered). Quite a bit of the floe appears to be rotated, stretched and rearranged as shown in the three levels of zoom. The 4th image shows the enveloping swath of 2º of latitude and even more dramatic ice ridges and fissures.

The lower part of the figure captures hourly positions of the Polarstern over 24 hours. This wild ride comes after relatively banal displacements since mooring on the floe on Oct 04.
« Last Edit: October 20, 2019, 03:37:53 AM by A-Team »

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Re: MOSAiC news
« Reply #143 on: October 19, 2019, 09:15:02 PM »
Here is more of a landscape view of the event. Click to play.

What happened to the buoys -- were any lost? No, all are reportingl Here it would be interesting to show locations of nearby buoys before, during and after. Since some of the 72 buoys deployed already by Mosaic are close to the Polarstern and report twice an hour, a sudden glitch in their positions would show ice mechanical failure happened catastrophically.

If the event unfolded relatively slowly over several hours or days (or if it is still ongoing in the next days), that too should show up clearly. Thus the buoy array provides a time-resolved history of the event at a finer scale possible with 1-2 daily Sentinel-1 imagery.

Buoy positions need to be plotted on top of a relevant lat,lon range on S1 imagery. A choice like 84-86, 130-134 might work for several weeks to come. Most of the buoys can sense and signal when they are in open water.

Attached are the last 227 hours the sailwx database to 19 Oct 2019 as csv. It does show some exceptional winds on the 19th and also some unexpected ship displacements post-mooring. I extracted those with a descending sort.
« Last Edit: October 20, 2019, 03:27:08 AM by A-Team »

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Re: MOSAiC news
« Reply #144 on: October 19, 2019, 11:40:12 PM »
I collected current positions of 69 Mosaic buoys on Oct 19th (after the event) from IADP's database. It is more tedious to collect them for Oct 16th (not done). I then subtracted buoy lat,lon from the current position of the Polarstern to obtain distances for latitude (0.1º is 11.1 km) and simple differences for longitude. The graphic captures some of the closest buoys. The full database is attached as a csv file.
« Last Edit: October 20, 2019, 03:33:53 AM by A-Team »

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Re: MOSAiC news
« Reply #145 on: October 20, 2019, 05:55:55 PM »
Another day or two and the Polarstern might be right back where it started from (first image). It turns out that PolarView is a full day ahead of mosaic_multisensor which will not post its map of Oct 20th until tomorrow.

We like to have the news here first: the animation (which needs a click) shows the movement over the last 18 hours. Some leads are narrowing; others may be freezing over. Note the later frame is S1A, the other is from S1B. The Polarstern's position is shown by a white star in the scene overview.

The 180 ms close-up (3x served by PolarView) shows things have not totally settled down at the floe. One has to wonder how Mosaic deals with distortions and displacements given electric and LAN cables are laid out a km or more onto the ice.

None of the images here are rotated; 135ºE is the vertical; south is up, Greenland is down. The ship voted to have north up in their maps which has unfortunate effects as the longitude changes. Sentinel 1AB images come perfectly aligned day after day; resolution and comparisons are , corrupted by rotation.

Technical note: If the 16-bit jp2 files had been used instead of 8-bit screenshots of the jpg offerings (and all the available dates since the 17th), image quality might significantly improve on enlarged floe time series.

An interesting issue arises matching contrast in images from different S1 satellites. Even if they carry the 'same' instrument, the viewing angle might be quite different and non-nadar over the floe as the 'filmstrips' show. One approach is to hold the sharper image fixed (after optimization exploiting the 16-bit) and adjust the second so that its histogram matches. This eliminates distraction arising from wildly different initial contrasts. The quickest way of doing that is using the middle slider (gamma) in Gimp's Level tool.

Ultimately, if floe surface roughness has changed between the two timestamps or if ridge reflections are taken from different orbital perspectives, the risk of artifacts remains. At some point though, given consistency between multiple scenes, Mosaic's selected floe itself must be changing.
« Last Edit: October 20, 2019, 06:53:28 PM by A-Team »

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Re: MOSAiC news
« Reply #146 on: October 20, 2019, 08:17:02 PM »
First amateur attempts towards a presentation of ice deformation. Here showing 3 mosaic buoys, chosen for their roughly equilateral relative positions using iabp coordinates to 4decimal place and Polarstern rough location to only 1dp, from day 281-291(earlier today). Polarstern coords are hourly and have been duplicated to match the 30m buoy coords.
300234068222000, Meeris Pbuoy
300234068225020 listed on iabp as IT (Ice tracker)
300234068226020, Meeris Pbuoy

Deformation is most noticable during day 286-7.
Distances shown are calculated using octave mapping which appears to produce results lower than that of the haversine method possibly due to the high latitudes. Will look into fixing that.
I haven't yet found PS location to more than 1dp
« Last Edit: October 20, 2019, 08:43:30 PM by uniquorn »

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Re: MOSAiC news
« Reply #147 on: October 20, 2019, 09:47:31 PM »
Quote
Meeris
Sea Ice Gateway --> Meer-Eis-Portal -- german--> Meereisportal
Sea Ice Gateway Questions-- german --> Meereisportalfragen
Sea Ice Gateway FAQs -- german--> Meereisportalfragenklarstellungen
Sea Ice Gateway staffer -- german--> Meereisportalfragenklarstellungenverantwortliche

Quote
I haven't yet found PS location to more than 1dp
Me either. We need to write a Meereisportalfragenklarstellungenverantwortliche about that. It should be served off the buoy list and in the legend to mosaic_multisensor. The ship should know its GPS better than any buoy -- maybe by the minute, which would be very interesting for acceleration if they are truly frozen. Bandwidth is limited but not that limited.

They also know stern-to-bow azimuthal angle (~heading/bearing) very accurately. Not seen it. The other issue are the tracks of both the PS and AF as they came and went to the floe. These have left 25m wide weaknesses in the ice that may account for current or future lead re-openings. The AK (UCKZ) turned off its beacon on 27th Sept.

Sailwx is peculiar mix of units: time in base60 rather than elapsed decimal UTC like unix, base60 lat,lon instead of base10, nautical miles, knots but temperatures in ºC. Some of the buoys report in AM/PM instead of 24 hrs. Nuisance in calculating elapsed times.

Should we be converting buoy profiler depths to fathoms? Calling in data from the nearest pay phone booth to an answering machine? The problem is mariners still using rolled nautical charts.

Quote
Why is a ship's speed measured in knots? ... By the late 16th century, sailors had begun using a chip log to measure speed. In this method, knots were tied at uniform intervals in a length of rope and then one end of the rope, with a pie-slice-shape piece of wood (or “chip”) attached to it, was tossed behind the ship.

The difference between N 85°00' and N 85°01' is 1/60 of 111111 m or 1850 m. The difference between E 132°42' and E 132°43' (at 85º.00') is (haversine) 161.5 m but at 84º it is 193.7 m. So sailwx is not reporting to a consistent accuracy.

It seems like we could use hourly sailwx to update PS's position from the latest S1AB but more dp are needed than sailwx provides. We are now 16 hours past that S1A which was ~18 hours from the last mosaic_multisensor.

Sailwx reports N 85°00' E 132°42' now whereas it was at N 85°00' E 132°48' at SIA but the satellite timestamp is to the second; the PS radar reflector was not at N 85°00' but rather N 84° and change. Note that "Where is Polarstern" --> Meereis --> sailwx.

So where are they getting these mediocre numbers from? How could they know the barometric pressure and wind speed if not from the PS's meteorological report? That has even worse lat,lon precision than sailwx. And reports in "local time" rather than UTC (though that is in the csv link).

The wind has picked up to 19 knots from 140º (Novaya Sibir) which is 35.2 km/hr. The rule of thumb is ice will move at 1% of that or 35 km/hr which pencils out to 8.4 km/day or 4.% longer than the base blue arrow in the legend to mosaic_multisensor. Because of the coriolis force and boundary conditions, the ice moves at a significant offset from the wind, here more SZ-ward.
« Last Edit: October 20, 2019, 09:56:19 PM by A-Team »

blumenkraft

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Re: MOSAiC news
« Reply #148 on: October 20, 2019, 09:55:41 PM »
Sea Ice Gateway staffer -- german--> Meereisportalfragenklarstellungenverantwortliche

Sea Ice Gateway FAQ-staffer to be precise.

And it's female. If you refer to a male one you need to add an R or an N at the end (depending on the sentence around). Which makes it a Meereisportalfragenklarstellungenverantwortlicher.

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A-Team

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Re: MOSAiC news
« Reply #149 on: October 20, 2019, 10:08:36 PM »
Staff is not likely to be empowered to provide information without supervisory approval from the Meereisportalfragenklarstellungenverantwortlicheabteilungsleiter.

The PS has yoyo-ed back to N 85°00' E 132°48' where it was 18 hours ago per sailwx, despite the steady wind from the south.

Some dimensions are noted on the lead that opened up on the 17th based on the 1140 pixels between 84.6 and 84.9º which is 3/10ths of a 111 km degree of latitude.
« Last Edit: October 20, 2019, 10:39:54 PM by A-Team »