Arctic Sea Ice : Forum

AGW in general => Developers Corner => Topic started by: Wipneus on February 05, 2019, 04:17:09 PM

Title: Test space
Post by: Wipneus on February 05, 2019, 04:17:09 PM
Thread used for testing images/animations. In my case an mp4 animation created with ffmpeg.

This image uses a -pix_fmt yuv420p option.
Title: Re: Test space
Post by: b_lumenkraft on February 05, 2019, 04:19:15 PM
Hey Wipneus,

this one is working fine on my Mac! Thanks a lot for doing this.
Title: Re: Test space
Post by: Niall Dollard on February 05, 2019, 05:25:47 PM
Tried it on two browsers. Chrome and believe it or not, IE 11, and it works fine.  :)
Title: Re: Test space
Post by: Sterks on February 05, 2019, 08:19:25 PM
 does not work in ipad (latest ios) either chrome or safari. Sorry
Title: Re: Test space
Post by: Wipneus on February 06, 2019, 09:49:15 AM
does not work in ipad (latest ios) either chrome or safari. Sorry

Not happy to hear that Sterks. Unfortunately I cannot test that device myself. What I can do is to find another file that works and compare with mine that does not. 

Are you able to see the mp4's that A-team posted, like in this post (and many others) :
https://forum.arctic-sea-ice.net/index.php/topic,1259.msg138898.html#msg138898
Title: Re: Test space
Post by: uniquorn on February 09, 2019, 04:08:09 PM
testing avi. testing mp4
settled on

 ffmpeg -i tst2.gif -crf 29 -pix_fmt yuv420p -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" tst2e.mp4

-crf 29 the higher the number the lower the quality, smaller file
-pix_fmt yuv420p better chance of working in all browsers (same as Wipneus)
-vf prevents odd number of frames

probably still doesn't work for everyone but tested ok in firefox and edge on win10
Title: Re: Test space
Post by: uniquorn on February 18, 2019, 12:35:51 AM
whoi itp107 test
Title: Re: Test space
Post by: sesyf on February 20, 2019, 04:31:13 PM
Perhaps it’s just me but my ipad / safari does not allow mp4 for some reason... I should try to find if it’s some setting or whatever. I get the ’run video’ icon with a slash over it...
Title: Re: Test space
Post by: uniquorn on February 20, 2019, 07:21:52 PM
No apple devices here to test with either but these specs are quite limiting for this forum. Ipad users may have to download and play (more efficient if played more than once) Please see https://airmore.com/play-mp4-on-ipad.html
Title: Re: Test space
Post by: uniquorn on April 20, 2019, 11:32:30 AM
h.264 test
ffmpeg -i rb2.gif -c:v libx264 -preset slow -c:a copy rb4.mp4
not working for me
Title: Re: Test space
Post by: Sleepy on April 20, 2019, 02:04:01 PM
Testing the above with quicktime and iOS compatibility options (which makes it a bit larger):
ffmpeg -i rb4.mp4 -vcodec libx264 -pix_fmt yuv420p -profile:v baseline -level 3 rb4-MAC.mp4
Title: Re: Test space
Post by: uniquorn on April 21, 2019, 12:35:57 PM
Thanks Sleepy. Will get around to reading the manual sometime. :)
@b_l you could try ImageJ (or Fiji which already has more plug-ins) though you may need gimp for transparency (alpha)
Title: Re: Test space
Post by: uniquorn on April 21, 2019, 01:55:27 PM
ascat last 50days test for mac
ffmpeg -i asc-mac.gif -vcodec libx264 -pix_fmt yuv420p -profile:v baseline -level 3 -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" asc-mac2.mp4
Title: Re: Test space
Post by: BenB on May 01, 2019, 10:37:19 AM
Testing
Title: Re: Test space
Post by: johnm33 on May 18, 2019, 03:41:48 PM
test gif
(https://media.giphy.com/media/SXmNU5byaWhAaMQIYP/giphy.gif)
test gif2
(https://media.giphy.com/media/ehOEW1ALd6bhtyd9VR/giphy.gif)
Title: Re: Test space
Post by: A-Team on May 22, 2019, 06:21:42 PM
Just seeing if ImageJ: 57 gif frames --> avi --> mov --> mp4 works using the free and fast online converter at https://www.freefileconvert.com/mov-mp4

It does works for me on a Mac and accomplishes a huge reduction in file size, from 90 to 3.3 MB making it feasible for the forum.

The movie shows the developing arm of the Beaufort Gyre as seen by Ascat from day 255 of 2018 (Sept 12th) to day 141 of 2019 (May 21st) using 5 day intervals except for the last 3 dates. This spans 251 days.

The question here is where and when does the ice arise. The arm begins to form over Banks Island very early in the freeze season. The ice is whitish, meaning that it is older thicker ice that has largely excluded salt from its initial brine channels meaning minimal surface polarizability sko better return of Ascat's radar beam.

The ice appears sourced from the upper eastern portion of the resilient CAA ice. The winds about the  Beaufort high cause a gyre to form that is however constrained by the fixed islands of the CAA. This appears as a slicing, with large leads developing in the ice too far east of Banks' promontory to participate, to the extent the ice had mechanical cohesion.

Gyre means circle. The Beaufort ice arm has never attained anything approaching a full circle in recent years. Instead, increasingly broken up floes move up the Alaskan coast up to the eastern Chukchi and then bend towards the pole where individual floes either dissipate completely or weakly persist by the end of the melting season. Ice inside the arm has been wrongly said to thicken in place over multiple years.

The' Beaufort Gyre' is an exceedingly vague concept geographically scarcely ever depicted in the same location at the same size. It is probably best defined operationally by the lowered salinity basin shown at depth by Mercator Ocean.

As an off-axial surface rotation on a non-inertial non-spherical reference frame that itself is rotating, the ice experiences centrifugal as well as positionally varying coriolis and buoyancy forces in addition to the wind stress field applied to floe edges and compression ridges.

Since large regions of the Beaufort have melted out in recent years, an additional complexity for figuring upward Ekman transport has set in because the wind forcing is now divided over the course of a year between a rigid complete ice pack, loose floes in open leads, and large patches of strictly open water.

The pack is not moving as a western boundary current in the sense the arm is well off the bathymetry of narrow continental shelf. If there is an operative Alaskan coastal current, it cannot be on the surface as countercurrent surface ice eddies are not seen (unlike in East Greenland). However ice production and tidal effects in the Amundsen Gulf do prominently affect a band of near-shore waters along the Alaskan coast, as does Mackenzie River discharge in season.

The Beaufort Gyre is depicted in scientific journals in wildly varying ways. One of the more extreme versions is hosted by NSIDC (left of 2nd image). This is at odds with the location of a reduced salinity basin at depth provided by Mercator Ocean (right of 2nd image) and observationally confirmed by profilers and gliders.

No fresh water reservoir exists anywhere in the Arctic Ocean (away from river discharge; recent Borneo expeditions have had to melt snow as ice melt was undrinkable. Oceanographers use 'fresh water' as a figure of speech for waters with slightly reduced psu salinity.

Beaufort waters at depth cannot cross over the shallow sills of the main CAA channels and so do not reach Baffin Bay or threaten Gulf Stream overturning in the North Atlantic. Net annual export is roughly 44,000 cubic km per year from the Arctic to Baffin Bay, a small portion of sverdrups coming in with the West Spitsbergen Current or leaving via the East Greenland Current.
Title: Re: Test space
Post by: gerontocrat on May 22, 2019, 06:54:32 PM
Just seeing if ImageJ: 57 gif frames --> avi --> mov --> mp4 works using the free and fast online converter at https://www.freefileconvert.com/mov-mp4

It does works for me on a Mac and accomplishes a huge reduction in file size, from 90 to 3.3 MB making it feasible for the forum.

The movie shows the developing arm of the Beaufort Gyre as seen by Ascat from day 255 of 2018 (Sept 12th) to day 141 of 2019 (May 21st) using 5 day intervals except for the last 3 dates. This spans 251 days.
Works fine - on Windows 10, Google Chrome (on-line and downloaded)

ps: need to find freebie mp4 and gif players that let me slow down the frames per second. My old eyes and brain can't keep up.
Title: Re: Test space
Post by: johnm33 on May 23, 2019, 01:06:14 PM
"ps: need to find freebie mp4 and gif players that let me slow down the frames per second. My old eyes and brain can't keep up."
right click/play speed works for me in firefox
Title: Re: Test space
Post by: A-Team on May 23, 2019, 09:47:12 PM
Testing the waters again on all-ImageJ Ascat mp4. Good labels can be made and positioned as desired if the files are renamed properly before loading. Duplicating the stack, cutting and filling to text box size, then enlarging canvas to fit final size of the data stack, using 'paste control' set to 'zero fill' which is ImageJ's way of setting pure black as alpha transparency.

I also compared 'equalize' to manual brightness and adaptive contrast as a quick and easy contrast adjustment. If an Ascat land mask is loaded, these tools have a better histogram to work with that does not include noisy weather patterns over open water. The land mask is helpful in defining crop boundaries. If it is included in the stack of Ascats, it will be cropped just like them and can be used at any time up to mp4 production.

The specific task here is optimally depicting movement of the last holdout ice between the North Pole and central CAA (which has poor inherent contrast). Normally it just sits there but over the last 172 days a great unprecedented swath of ice has steadily moved from islands off central Siberia across the pole nearly to and out the Fram. The older ice is been squashed up against the Canadian islands, with some pushed towards the Beaufort, some forced through Nares, some possibly to the Barents, with most going down the Fram. The Ascats are again spaced at five days to reduce file size of product.

Despite wx predictions to the contrary, this pattern has continued through May 22nd. This, if it continues another month, will lead to shocking developments by fall so I am inclined to bury the mp4 here in development where fewer will get unduly alarmed ahead of events. Even with a so-so melt season, there would be very little surface area, volume, or multi-year ice left going into September. However we have seen other years like 2012 where weather simply shifted and the melt season trajectory changed to something less damaging.

It's never been clear what would hold the old ice against the Canadian islands if the outer ice pack is not there to exert pressure; wind patterns could well change with more open water, this ice might drift off, be broken up by waves, with its remnants disappearing.

Some movements of continuously recognizable features are shown in the static image. It is better to circle reference areas than to use vectors of point displacements because of rotation and deformation. The dark ice is mostly first year and so the displacement of its front is feasible to measure. For scale, it is 1050 km from Longyearben, Svalbard to the North Pole.

The attached high precision land mask is from AMSR2UHH. It fits very accurately over the 1170 x 1170 Ascats.
Title: Re: Test space
Post by: A-Team on May 24, 2019, 07:23:04 PM
Here I am testing a few other ImageJ processes while looking at the question of whether the massive ongoing Arctic Ocean icepack rotation is leading to significant export out the Svalbard-FJL opening to the Barents (where it would very likely melt away later in the season. While the answer to that is no for the last 30 days (to 23 May 2019, day 143), more ice will be shaved off into a path between the islands if the current wind forcing continues.

However the amount would be negligible compared to the area/volume exiting the Fram. The ice in the Barents today predominantly derives from left-over ice of the previous melt season and ice leaving the Kara Sea. Last year, the Kara injected a massive tongue of ice north into the Arctic Ocean basin, some 5-6% of the total area. This ice moved zonally west but did not quite make it to the Fram.

On the technical side, the first image shows a developing seasonal problem with Ascat: as more open water develops, image quality degrades and ice features can scarcely be distinguished from increasing dielectric in fo,g low clouds and surfaces enriched in sea salt. This affects boundary areas like the Bering/Arctic, Chukchi/Arctic and Barents/Arctic almost all year.

The aim here is to extend the Ascat season into June by masking both islands which contribute distraction in time series but are fixed in position and open water/regions of low concentration ice as determined by AMSR2 which is not subject to the same artifacts. The former is a fixed mask that is valid all year; the latter varies from day to day.

The first image shows the Ascat download (top) for May 2nd compared a white fringed island mask (bottom) from UHH AMSR2 that stays fixed throughout the animation (2nd image). There are issues in resizing the mask within small channels between islands because 'large' pixels can only do so much. The second frame shows open water and the third what 0-20% ice concentration adds to the mask (red band). The AMSR2 has to be enlarged here by 7% to fit the 2.5x enlarged Ascat. It would have been better to have chosen the original Ascat enlargement properly (228.084%) as in 3rd graphic.

There are no no real additional steps involved in placing daily variation masks over montaged enhanced Ascats. The AMSR2 itself cannot be enlarged by non-integral amounts with interpolation of palette steps which would disrupt precision color picking from it.

Some text to orient non-experts has been included by placing black text in a blank alpha channel over any frame, then duplicating to the total number of frames, removing the alpha channel to white, inverting, and placing it over the ImageJ montage with 'copy control' set to black as transparent. Date labels come from the original file names, as modified, and are captured early on (before ImageJ loses them).
Title: Re: Test space
Post by: SteveMDFP on May 24, 2019, 07:28:29 PM
Here I am testing a few other ImageJ processes while looking at the question of whether the massive ongoing Arctic Ocean icepack rotation is leading to significant export out the Svalbard-FJL opening to the Barents (where it would very likely melt away later in the season. ...

It is so good to have A-Team back on the Forum.  Such combined clarity and sophistication is a rare treat in any realm.
Title: Re: Test space
Post by: wili on May 24, 2019, 08:02:37 PM
Hear! Hear!
Title: Re: Test space
Post by: uniquorn on May 24, 2019, 11:31:08 PM
Good ideas for cleaning up the images but ascat often 'sees' ice that unihamburg amsr2uhh doesn't. Example is the never melting ice in the beaufort/chukchi last september, 20180902,day245 shown here.(apologies for the rough cropping/scaling)
Also amsr2 has it's own 'flashing' 'scorching' and other 'weather' issues.

Title: Re: Test space
Post by: A-Team on May 25, 2019, 06:09:18 PM
Here I am testing another double-masking of Ascat, this time with U Bremen SMOS-SMAP new thinness product instead of UHH AMSR2 low sea ice concentration and open water. This product is provided at a very generous scale of 1173 x 2170 png, a big improvement in resolution (if it is real and not just a rescale). It comes with a satisfactory land mask too.

https://seaice.uni-bremen.de/data/smos_smap/png/north/2019/ png archive back to 31 Mar 2015

Because thinness and concentration are fairly similar in location in that edges of the ice pack have thinner ice as well as lower ice concentrations, it isn't feasible to triple-masking because of the extensive overlap in areas affected.

This combination of two satellites seemed to have extended the season well past the previous SMOS-by-itself terminal date of May 1st. However farther along in the season as melt ponds and liquid clouds become important, both the SMOS-SMAP thinness and Ascat products will likely deteriorate (or the former not even be archived).

The mp4 shows 53 days from April 1st to May 23 of 2019. A larger view is needed because ice thinness in peripheral seas such as Bering, Barents and Kara is more important than in the central Arctic Ocean this time of year. Both SMOS-SMAP and Ascat have a few missing days or partial images which I replaced by adjacent complete ones; this happens as well with UHH AMSR2 but less frequently.

The May 23rd looks like it has a blob of weather in the northern western Beaufort interfering with proper thinness determination. Ice thinness doesn't change as rapidly as weather or melt or and persists from frame to frame. These artifacts could be edited out manually or by AI per the criteria stated.

On scaling, SMOS-SMAP needs an enlargement of 104.414 to fit the smaller AMSR2uhh whereas Ascat needs 228.084 so to match SMOS-SMAP to Ascat requires 228.084/104.414 = 218.442 magnification of Ascat. I measure from the Aleutians to southern Sweden to get the largest pixel lengths to compare as this reduces percent error in the scaling ratio.

The AMSR2 masking shown a couple of posts back covered 30 different days so I am not reposting it here. "30 days of Ascat land and water masked to 24 May 2019.mp4"

Quote
Combined SMAP–SMOS thin sea ice thickness retrieval
C. Patilea et al U Bremen AWI 28 Feb 2019
https://www.the-cryosphere.net/13/675/2019/ free full text

Consistent Combination of Brightness Temperatures from SMOS and SMAP over Polar Oceans for Sea Ice Applications
AU Schmitt, L Kaleschke April 2018
https://www.mdpi.com/2072-4292/10/4/553/htm free full text

https://seaice.uni-bremen.de/data/smos_smap/png/north/2019/ where to get the pngs

The passive microwave sensors Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) provide brightness temperature data at 1.4 GHz. At this low frequency the atmosphere is nearly transparent and in polar regions the thickness of thin sea ice can be determined up to 0.5m for an extended period into the spring.

The thickness of ice partly determines the resistance against the deforming forces of wind and ocean currents. Even a thin layer of sea ice inhibits evaporation, reduces heat and gas exchange between ocean and atmosphere and increases the albedo. Sea ice — even if thin — also provides a solid surface for snow to deposit on, which further reduces heat exchange and increases albedo.

SMOS has been developed for retrieving soil moisture by inferring the surface emissivity which is correlated with the moisture content and sea surface salinity and link measured brightness temperatures with sea salinity through the dielectric constant of the water in the first few centimeters [[to which upwardly extruded brine or melt ponds might contribute]].

Quote
Effects of decimetre-scale surface roughness on L-band Brightness Temperature of Sea Ice
M Miernecki, L Kaleschke et al  03 Jun 2019
https://www.the-cryosphere-discuss.net/tc-2019-110/tc-2019-110.pdf free full text

Sea ice thickness measurements with L-band radiometry is a technique which allows daily, weather-independent monitoring of the polar sea ice cover. The sea-ice thickness retrieval algorithms relay on the sensitivity of the L-band brightness temperature to sea-ice thickness. In this work, we investigate the decimeter-scale surface roughness as a factor influencing the L-band emissions from sea ice.

Most affected by surface roughness is the vertical polarization around Brewster's angle, where the decrease in brightness temperature can reach 8 K. The vertical polarization for the same configuration exhibits a 4 K increase. The near-nadir angles are little affected, up to 2.6 K decrease for the most deformed ice. Overall the effects of large-scale surface roughness can be expressed as a superposition of two factors: the change in intensity and the polarization mixing. The first factor depends on surface permittivity, second shows little dependence on it.
Title: Re: Test space
Post by: b_lumenkraft on May 25, 2019, 06:30:46 PM
That's quite an amazing result! Great work A-Team.
Title: Re: Test space
Post by: sark on May 26, 2019, 10:07:38 AM
 1000mb temperature anomaly by month, 2012-2018 vs 1979-2000

tiled in gimp with python
Title: Re: Test space
Post by: A-Team on May 26, 2019, 10:23:13 PM
'Wind roses' are produced by weather stations to succinctly summarize wind direction and strength seasonally or over a year. Typically, the wind direction is binned into the 16 cardinals (eg SSW), wind speed is binned into color, and wind frequency of a given direction displayed continuously as spoke length in these 'directional histograms'.

The first image below collects various depictions of wind roses, including on for the Svalbard weather station. The links show how to roll your own from raw data with code or even entirely within excel, plus a journal paper on actual North Atlantic wind roses and vorticity.

https://www.gigawiz.com/windrose.html
https://www.climate.gov/maps-data/dataset/wind-roses-charts-and-tabular-data#undefined
https://windroseexcel.com/guides/using-excel-make-wind-rose-step-step-guide/
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JC012453 free full

It would be feasible to pick any (gridded) point in the Arctic Ocean, collect recent and predicted GFS data in nullschool and make a 2m wind rose. However how accurately are wind speed and direction really known in the un-instrumented situation? (Note buoys drift around and moorings do not monitor surface conditions.)

Now Ascat and QuikSCAT were actually designed to measure surface winds on the open ocean via Bragg backscatter from wind-generated capillary-gravity waves. That might work for open water of the Arctic Ocean in late season though we've never looked. Ascat can be repurposed for ice just like the soil moisture satellite SMOS can be repurposed for ice thinness.

Since surface wind data is not at hand but near-daily ice motion is, I looked at whether 'ice roses' could be made from T Lavergne's OSI SAF gridded sea ice motion vectors.

ftp://osisaf.met.no/prod/ice/drift_lr/merged/ ice motion .nc files
https://tinyurl.com/y4b6qblq daily ice motion map

Now daily data is online in properly geocoded netCDF but I elected to prototype with a hack on the graphical product of the last 90 days. Among other things, I expected ice roses to show (1) ice NOT gyrating in the Beaufort 'Gyre', (2) regular rapid ice motion Chukchi-ward off the Alaskan coast, (3) a broad swath of rapid ice motion towards the Fram, and (4) nearly dormant thick ice above the CAA.

ImageJ, under 'Z project, provides various ways of making ice roses out of an ice motion stack. These are not ideal because of the 3x scale, original arrowheads and magenta coloring for uncertain motions. The 'Volume Viewer' plugin has much fancier ways of looking stacks (3rd illustration; inset shows a 5x5 grid square from the Ak Beaufort compared to southern CAB/
Title: Re: Test space
Post by: A-Team on May 27, 2019, 06:55:38 PM
Here I am testing another double-masking of Ascat, this time with U Bremen SMOS-SMAP new thinness product instead of UHH AMSR2 low sea ice concentration and open water. This product is provided at a very generous scale of 1173 x 2170 png, a big improvement in resolution (if it is real and not just a rescale). It comes with a satisfactory land mask too.

https://seaice.uni-bremen.de/data/smos_smap/png/north/2019/ png archive back to 31 Mar 2015

Because thinness and concentration are fairly similar in location in that edges of the ice pack have thinner ice as well as lower ice concentrations, it isn't feasible to triple-masking because of the extensive overlap in areas affected.

This combination of two satellites seemed to have extended the season well past the previous SMOS-by-itself terminal date of May 1st. However farther along in the season as melt ponds and liquid clouds become important, both the SMOS-SMAP thinness and Ascat products will likely deteriorate (or the former not even be archived).

The mp4 shows 53 days from April 1st to May 23 of 2019. A larger view is needed because ice thinness in peripheral seas such as Bering, Barents and Kara is more important than in the central Arctic Ocean this time of year. Both SMOS-SMAP and Ascat have a few missing days or partial images which I replaced by adjacent complete ones; this happens as well with UHH AMSR2 but less frequently.

The May 23rd looks like it has a blob of weather in the northern western Beaufort interfering with proper thinness determination. Ice thinness doesn't change as rapidly as weather or melt or and persists from frame to frame. These artifacts could be edited out manually or by AI per the criteria stated.

On scaling, SMOS-SMAP needs an enlargement of 104.414 to fit the smaller AMSR2uhh whereas Ascat needs 228.084 so to match SMOS-SMAP to Ascat requires 228.084/104.414 = 218.442 magnification of Ascat. I measure from the Aleutians to southern Sweden to get the largest pixel lengths to compare as this reduces percent error in the scaling ratio.

The AMSR2 masking shown a couple of posts back covered 30 different days so I am not reposting it here. "30 days of Ascat land and water masked to 24 May 2019.mp4"

Quote
Combined SMAP–SMOS thin sea ice thickness retrieval
C. Patilea et al U Bremen AWI 28 Feb 2019
https://www.the-cryosphere.net/13/675/2019/ free full text
https://seaice.uni-bremen.de/data/smos_smap/png/north/2019/ where to get the pngs

The passive microwave sensors Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) provide brightness temperature data at 1.4 GHz. At this low frequency the atmosphere is nearly transparent and in polar regions the thickness of thin sea ice can be determined up to 0.5m for an extended period into the spring.

The thickness of ice partly determines the resistance against the deforming forces of wind and ocean currents. Even a thin layer of sea ice inhibits evaporation, reduces heat and gas exchange between ocean and atmosphere and increases the albedo. Sea ice — even if thin — also provides a solid surface for snow to deposit on, which further reduces heat exchange and increases albedo.

SMOS has been developed for retrieving soil moisture by inferring the surface emissivity which is correlated with the moisture content and sea surface salinity and link measured brightness temperatures with sea salinity through the dielectric constant of the water in the first few centimeters [[to which upwardly extruded brine or melt ponds might contribute]].
Title: Re: Test space
Post by: Jim Hunt on May 27, 2019, 07:07:23 PM
This combination of two satellites seemed to have extended the season well past the previous SMOS terminal date of May 1st. However farther along in the season as melt ponds and liquid clouds become important, both the thinness and Ascat products will deteriorate.

Note that although the SMOS images are readily available for download if you know where to look they are not accessible via the Bremen data browse interface, which states "no data during summer":

https://seaice.uni-bremen.de/databrowser/#p=smos

Use with care?
Title: Re: Test space
Post by: Jim Hunt on May 28, 2019, 05:31:18 PM
Testing whether this animation autoplays or not:

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=382.0;attach=121402;image)

For context see:

https://forum.arctic-sea-ice.net/index.php/topic,2591.msg201758.html#msg201758
Title: Re: Test space
Post by: A-Team on May 28, 2019, 05:56:48 PM
Quote
SMOS images are available for download if you know where to look; they are not accessible via the Bremen data browse interface, which states "no data during summer. Use with care.

Right, the interface discourages use of summer SMOS probably because some people wouldn't use it with care and subsequently diss the product. It must be hard to separate information from noise though or they would have done so. However there's no secret link to the summer archive, just the usual: https://seaice.uni-bremen.de/data/smos/png/

SMOS Level 1C v6.20 goes throughout the summer back to 2012. The png though are a meagre 275 x 275 pixels for the Arctic Ocean proper, needing 132.54% enlargement just to overlay Ascat and 302.05% to overlay the smaller AMSR2 ice concentration.

For reasons given in the 2019 article above, SMOS-SMAP probably improves on plain SMOS. However we don’t know at this point whether SMOS-SMAP will continue on into June or through the summer. I expect so because it is easier just to leave the pipeline running than shut it off and then back on.

https://seaice.uni-bremen.de/data/smos_smap/png/north/2019/ png archive for SMOS-SMAP

Another direction taken by L Kaleschke et al to improve SMOS is pairing it with CryoSat-2 swaths to extends its thickness down to 1m. However I believe that shuts down on May 1st because of summer dielectric issues.

So the question is, if the Ascat record goes all year but is overlain with unfixable contrast artifacts in summer, how do we best mask those in order to still visualize sea ice motion (especially in view of MOSAiC floe anchorage and trajectory)?

It helps somewhat to mask land, open water, and low concentration in Ascat but thinness and thickness are still problematic. Very few current journal articles on sea ice thickness even mention Piomas, possibly because it is not observational nor testable in situ. That leaves thinness and IceBird.

https://www.awi.de/en/science/climate-sciences/sea-ice-physics/projects/ice-bird.html
https://epic.awi.de/id/eprint/47841/1/CampaignReport_ASIMBOsummer2018_final.pdf

"The analysis shows that the largest fraction of surveyed sea ice in 2018 originated in the Laptev Sea. It took approximately 2–3 years of drift with the Transpolar Drift until ice reached Fram Strait." (2nd image below)

Below I tested whether we could get a better Ascat image for the single mid-summer date of 01 Aug 2018, with a method that would carry forward to the current season. The final frame asks whether the 0.5m thinness boundary is trackable despite its artifacts.

Once again, the motivation is that ice areal export this year may exceed in situ areal melt — wind-driven ice movement being a critical consideration in addition to seasonal clouds, melt ponds, insolation and radiative balance. Ascat is about the easiest tool for measuring ice areal export and lagrangian trajectories of extended features, important as very little ice resides in distinctive floes outside the Beaufort streamer.

It's quite difficult to continuously track sea ice motion credibly over multiple years because of the summer microwave data hiatus, yet MOSAiC would like to know an accurate locational history of the floe the Polarstern will be anchoring up to for the year. For a back-trajectory approach, see:

Arctic warming interrupts the Transpolar Drift and affects long-range transport of sea ice
T Krumpen et al April 2019
https://www.nature.com/articles/s41598-019-41456-y

SMOS-SMAP may be done for the summer -- or they can't make product on Ascat glitch days. Here are the offerings on their server, version 205 of the algorithm has just recently kicked in:

2019: daily to May 23rd, version 205 [today is May 28th!]

2018: hiatus from June 5th to August 7th and Oct 8th to Dec 31st, version 100
20180604_north_mix_sit_v100.png
20180809_north_mix_sit_v100.png

2017: December only, version 100
20171201_north_mix_sit_v100.png
20171231_north_mix_sit_v100.png   

2016: nothing

2015: full year version 100
Title: Re: Test space
Post by: Jim Hunt on May 28, 2019, 07:43:11 PM
For reasons given in the 2019 article above, SMOS-SMAP probably improves on plain SMOS. However we don’t know at this point whether SMOS-SMAP will continue on into June or through the summer. I expect so because it is easier just to leave the pipeline running than shut it off and then back on.

I have my own pipeline running to acquire images, but currently it simply assumes yesterday's date. I'll need to work on that since the latest SMOS-SMAP image seems to be from the 23rd. Does the apparently < 0.5 m thick area at ~78 degrees north of Utqiaġvik exist in the real world?

Quote
Another direction taken by L Kaleschke et al to improve SMOS is pairing it with CryoSat-2 swaths to extends its thickness down to 1m. However I believe that shuts down on May 1st because of summer dielectric issues.

I've been acquiring the NetCDFs for a while. The most recent is for the week beginning April 21st.
Title: Re: Test space
Post by: A-Team on May 28, 2019, 08:15:31 PM
Quote
Does the < 0.5 m thick area at ~78 degrees north of Utqiaġvik exist in the real world?
This feature was discussed above along with techniques for manual or AI discrimination between weather artifact vs flash melt vs ice thinness . Another couple of days of SMOS-SMAP data are needed for sandwiching.

The IceBird reports make for interesting reading. One of several observational ice thickness data images from a low elevation August 2018 flight out of Alert is shown below.  Coverage is limited to flight tracks but still very worthwhile for high resolution calibration and reality checks. The March/April 2019 report is not yet posted; we can wonder if it will incorporate Polarstern's serendipitous in situ data from the early March reverse surge of the Fram.

https://www.awi.de/en/science/climate-sciences/sea-ice-physics/projects/ice-bird.html
Title: Re: Test space
Post by: Jim Hunt on May 29, 2019, 12:04:14 AM
ICESat-2 data has dropped. However my alter ego is having difficulty finding the sea ice thickness numbers:

https://twitter.com/GreatWhiteCon/status/1133480350200545281
Title: Re: Test space
Post by: A-Team on May 29, 2019, 07:43:14 PM
The first mp4 below tests whether Ascat is able to display trackable ice feature motion in late summer and fall using 5-day increments. The first frame (red arrows) shows a noxious weather system on 25 Aug 2018 that cannot be removed by land and open water (AMSR2) masking or adaptive contrast enhancement.

However the other 26 days to 02 Jan 2019 show stable ice motion features. Thus by removing late summer dates with transient passing weather from the time series, it may be feasible to track a few features well into June and well back into August, possibly even attaining the holy grail of (multi) year-round tracking of the entire icepack by establishing a sufficient subset of floe trajectories.

For vital observational projects like full-year MOSAiC, this could provide the history and conditions that the anchoring site experienced in the past.

The second mp4 compares raw Ascat (UL) to double-masked and mildly enhanced Ascat (UR), to o double-masked and strongly enhanced Ascat with moderate sea ice concentration in pink (LL)), to land- and open water-masked false color of mildly enhanced Ascat (LR).

These are best viewed over and over in loop mode (right-click mouse contextual menu) because only 27 days of data were used.
Title: Re: Test space
Post by: A-Team on May 31, 2019, 01:34:13 AM
Here I am testing whether ice motion vectors from osisaf really go all that well over Ascat time series motion of persistent features as masked for land and daily open water. Even though the Beaufort streamer has all but disappeared in Ascat except for the Chukchi by 26 May 2019, the arrows go quite well with perceived motion and feature displacement. Thus the colored contours provide the line integral of the daily osisafs.

The movie shows enhanced Ascat, followed by Ascat features, followed by osisaf arrows over Ascat, followed by osisaf arrows over Ascat features over Ascat. It looks more like a 5x4 slide show than a movie because the frame rate is set at one second. It would be feasible to do the whole melt season in this manner.
Title: Re: Test space
Post by: Jim Hunt on May 31, 2019, 03:21:08 PM
ICESat-2 data has dropped.

NSIDC have got back to me:

Quote
Since the data were just released yesterday, published papers aren't likely to be available yet, but they'll almost certainly be forthcoming. Here's a link to the NASA ICESat-2 website list of publications: https://icesat-2.gsfc.nasa.gov/publications if you want to check there occasionally for new content.

We don't yet have an idea of when the gridded products will be made available due to the many variables in play considering that Level 3B products comprise Level 0 - Level 3A data sets as inputs. I don't know if you've browsed the NSIDC ICESat-2 project page yet, but here's a link detailing the products available, expected, and the processing workflow: https://nsidc.org/data/icesat-2/products/

The ATL10 (ATLAS/ICESat-2 L3A Sea Ice Freeboard, https://nsidc.org/data/atl10/versions/1) data set outputs total freeboard height (height from top of snow/air interface to sea surface) where it can be calculated from also measuring sea surface height. For a highly detailed explanation of the processing steps and data output of ATL10, you may be interested in reading through the Algorithm Theoretical Basis Document (ATBD) for ATL10 available from this page: https://icesat-2.gsfc.nasa.gov/science/data-products

CPOM have also suggested some light bedtime reading matter:

https://twitter.com/GreatWhiteCon/status/1134091514274037760

A gridded sea ice thickness product still seems to be some way off however.  :(
Title: Re: Test space
Post by: A-Team on May 31, 2019, 06:17:14 PM
Please, test-forum material here only: graphic experiments.

Testing various combinations of masks and markups for interpretive effectiveness just on one day, 30 May 2019 (that continues the 5-day of the previous post), as it had an especially revealing Ascat for the Beaufort/Chukchi side. The file size is small so posted as a gif rather than mp4.

The first frame AMRS2 of the 'same' date provides land, open water and 50 palette bins intermediate concentration sea ice; Osisaf the sea ice motion from two days of AI. The latter needs a 85.123% reduction to fit over 6.25 km AMSR2, the scale here until the final reduction to 700 pixel width.

The Beaufort streamer is deteriorating so rapidly that the open water mask actually degrades the view in regions of scattered floes which are quite visible already in the enhanced Ascat. The open water mask remains very useful over the Bering and Chukchi seas, in the Fram and around Svalbard-FJL.

These images don't come with no time stamps because they are swath assemblies; sea ice motion is so rapid at ~1 km/hr in the Beaufort and quite heterogenous across the overall icepack so swath offset between different satellites leads to slightly incorrect masking.

The Osisaf overlay shows an approximate clockwise rotation of the entire ice pack, which has been going on fairly steadily for an over six months. The center of rotation is neither the North Pole nor the 'Beaufort Gyre' but better approximated by the Arctic pole of inaccessibility at 85º 48N, 176º 09E.

The maximal possible rotational (without hitting land) has radius 1118 km (excluding the small De Longa islands ) but in late May the radius appears rather larger, giving rise to a semi-circle of sea ice motion that takes ice off Banks Island all the way around the Siberian side to the Fram.

Indeed the Kara Sea has been swept up in this, exporting short-lived ice to the Barents instead of massively to the Arctic Ocean like last year where it was not fully exported out the Fram by the end of melt season.

There does not seem to exist a single optimal combination of overlays in melt season that works for every region. Consequently, it works better to prepare an interpretive packet. The May 30th data substantially clarifies (mis)interpretations arising last week from weather and ice surface disturbances, meaning Ascats will continue to provide good data into June but RT or NRT analysis should be deferred or restricted to a few scenes earlier as the last date lacks necessary flanking context.

The seven frames here for May 30th would best reside in ImageJ as a hyperstack. Each frame could be viewed horizontally in the time direction or vertically in the overlay. However only 0.5% of forum viewers use ImageJ.

We've looked before at automating production. Daily data downloads already present issues such as archive posting delays and omissions, as well as defective but patchable imagery. Patching is separately scriptable at least for Ascat and AMSR2. Once the image files are all in their expected desktop location, it is feasible via an ImageJ macro of macros to upload, rescale, adjust contrast, align to the pole, and assemble into a stack that could be added to the existing hyperstack as a new 'frame'. The question is, how flexible would such an automation pipeline be. Not very.
Title: Re: Test space
Post by: A-Team on June 02, 2019, 08:24:27 PM
Here I am testing a throwaway method that enable me to quickly see if the current day continues the incredible sequence of over 180 days of consecutive anti-cyclonic ice rotation. The example simply jiggles back and forth between May 31 and June 01. Indeed this is effective for this purpose. (We have tried other options over the years such as 'color interferometry' of three consecutive days which works but is harder for non-specialists to understand.

The second animation tests an algo for making a quick daily "executive summary" of the most recent developments. It uses AMSR2uhh for land and open water masks, osisaf for quantitative gridded vectors of ice motion, Ascat, ImageJ enhancements of that Ascat, and composition to final image within Gimp. The only technical part is floating arrows off the osisaf in a non-obtrusive but still visible overlay.

The third mp4 tests whether very fast (80ms) back and forth looped display over the 15 Mar -01 Jun 2019 early melt season is visually effective in understanding cumulative sea ice motion which has been truly extraordinary the last 6-7 months.

Towards the end, it shows (rainy?) weather coming in from Alaska over the Beaufort. The file size is so small at this speed at 1.2 MB that a whole year could be shown under forum size limits, possibly even two if water and land masking had been applied.
Title: Re: Test space
Post by: be cause on June 02, 2019, 09:59:11 PM
 .. cheers for what you are doing here A-team .. I can just @ press play and type .
but   wow ! that shows how big a biter Nares is very clearly .. and how much has left ,stage right . That is/was a lot of the oldest and the coldest ice  in the Arctic . Looks like we are going to find out what 80% plus of 1st year ice looks like in a challenging season . b.c.
 
 
Title: Re: Test space
Post by: A-Team on June 02, 2019, 10:17:17 PM
Quote
bc: Nares a lot of the oldest and the coldest ice in the Arctic is leaving. a challenging season.
Right. Am I just documenting an unusual start to a melt  season or writing the Arctic ice obituary? This persistent CW circulation has been devastating for remnant thicker ice. In addition to direct export, a lot of ice is being translocated to areas like the Chukchi where it will melt out even in a so-so summer (along with almost all the first year ice, the dark ice in Ascat). We've seen all these pieces before but not in concert for so long; we've also seen the summer weather change to something else.

Below I am just testing some very basic one-click enhancements of Worldview natural color of the Beaufort Sea on 01 Jun 2019 and looking to see if Ascat can see individual floes. These modifications are available in about any image program on any device including phones. However few forum posts clarify images.

The first 'as is' frame shows WV has deplorable initial contrast: whitish clouds over whitish floes next to snow covered land. If not looking for melt ponds, a linear contrast adjustment (frame 2) followed by local adaptive contrast enhancement (frame 3), followed by some unsharp mask (frame 4), followed by sometimes useful palette inversion (frame 6) show much better details of floe cracking.

If the original image had instead been a time series, those images can be stacked or montaged side by side and the enhancements applied to all of them at once with the same single clicks. This gives much more effective animations.

The first frame's lower inset shows Ascat of the same day at 4x. It can indeed detect individual large floes but not nearly as well as WorldView. The largest flow -- the one with the full-length fracture -- is 61 km in length. It is represented in Ascat by only 15 pixels. The hair-line fracture cannot be seen. Its best resolution in WorldView is shown in frame 5.
Title: Re: Test space
Post by: oren on June 02, 2019, 10:47:22 PM
A-Team, may I ask your permission to occasionally post some of the outstanding stuff here onto the main melting season thread? I think it deserves a wider audience even if by your standards it's just test material.
Title: Re: Test space
Post by: be cause on June 02, 2019, 11:00:04 PM
.. seconded :)
Title: Re: Test space
Post by: A-Team on June 03, 2019, 01:02:15 AM
Hi Oren, feel free to distribute and add commentary anywhere you see fit. I believe you can just link to the graphic alone, no need to download and re-upload, but have not tested that for all file types.

I still have some more pieces to test here such as more Google Earth Pro files. (They are an export/re-display option for netCDF .nc files out of Panoply.) For now, these are attached as .txt even though they are really .kml. GEP is now free but still prone to inexplicable crashing.

The attached image shows a new boundary polygon for the Arctic Ocean proper. This basin is where ice area, volume, extent and concentration matter. The rest -- like the Barents, Bering, Baffin and so forth -- just contribute background noise to inter-year comparisons. (Export is a ratcheting process.) The problematic relationship of DMI's 80ºN temperature circle to the Arctic basin is indicated.

Yesterday had quite an unusual Osisaf ... just about the entire ice pack was rotating though not quite about the maximal center of rotation (pole of inaccessibility). Some ice gets shaved off by Nord, Greenland and exits the Fram. There has not been consequential ice export out the Svalbard-FJL gap this melt season.

See also:

Barnes, R. (2019). Optimal orientations of discrete global grids and the Poles of Inaccessibility. International Journal of Digital Earth, 1–14. doi:10.1080/17538947.2019.1576786

Arctic Pole Rees et al. (2014) 176.149 85.802 1007.6039 1008
Arctic Pole GSHHG 176.1423 85.8015 1007.6777
Arctic Pole OpenStreetMap 176.2386 85.7911 1008.9112

Global Self-consistent, Hierarchical, High-resolution Geography (GSHHG)coastline data (Wessel and Smith 2016)
 
G Rees et al 2014.
Finding the Arctic Pole of Inaccessibility.”
Polar Record 50 (01): 86–91. doi:10.1017/S003224741300051X.
Title: Re: Test space
Post by: A-Team on June 03, 2019, 07:45:29 PM
Here I am testing the limits of Ascat enlargement and contrast enhancement for depicting ice movement in the core thick CAB ice from Sept 2018 to June 2019. The original starting Ascat is shown in the lower left corner exactly as offered at its online archive, cropped to the same view.

While some areas of ice above and to the west of Ellesmere hardly seem to move over the 256 days, other large and normally immobile areas below the pole are moving rapidly towards and out the Fram. If this pattern of ice pack motion continues, it will devastate the core of thick multi-year ice remaining, even with so-so melt season thermodynamics. The motion is far more extreme than 'trans-polar' drift as that is usually depicted.

On the technical side, the passages of the CAA are masked out as they were just adding distraction. Open water masking is not needed for this area. Ascat histograms are misleading, even not including land and water, because the older ice (whiter colors) is more confined to a specific region than first and second year ice.

After linear contrast adjustment, it benefits from gamma correction prior to subtle adaptive contrast and unsharp masking. It is easy to overdo this, giving an outcome that is too lumpy in appearance.

A single frame from DMI's Lincoln Sea is shown for June 2nd. This too could be animated though it would not be feasible to match dates exactly because of clouds. The same could be done in WorldView, skipping exact date matching to favor less cloudy days close in time. However the Arctic is a very cloudy place.
Title: Re: Test space
Post by: A-Team on June 04, 2019, 05:40:50 PM
Just testing if direct .avi to mp4 out of ImageJ displays after https://www.media.io/convert/mov-to-mp4.html. Seems like it works ok.

The interest here is not so much the Beaufort arm as along the coastline to the east, which is getting engaged these last few days. This, if it continues, would draw even more of the oldest thickest ice into warmer seas where it would melt out.
 
The initial gif was made using the animator at Worldview. Since it is limited to 40 days, I made two animations and concatenated them in ImageJ to get from April 10th (when the drama started) to June 3rd. Optical imagery is not available too much earlier because of winter darkness.

These images were gathered at the 1km resolution setting. They are fairly hard to enhance other than linear contrast squeezing. I also applied a very slight adaptive contrast to sharpen, converted to grayscale and inverted. The dates are floated in from a cropped duplicate as WV provides no control over their placement.

I'll post the key region farther east in a bit as June 4th becomes available, along with the Ascat view. Some of the action can already be seen in the latter. It has been far too cloudy above the Nares funnel to make a time series in the visible wavelengths; DMI's Greenland imagery is cropped too close to shore.

The core of thickest least mobile ice is under attack on the Fram, Nares and west CAA fronts. This will greatly increase the effects of melt season on the overall ice pack.
Title: Re: Test space
Post by: b_lumenkraft on June 04, 2019, 07:11:44 PM
Awesome contrasts A-Team. This is perfect!
Title: Re: Test space
Post by: longwalks1 on June 05, 2019, 06:44:09 AM
I am sure there are buttons or drop-downs for gui video players. 

For mpv  -- to slow it down
Code: [Select]
mpv --speed=0.1 78\ days\ fast\ back\ and\ forth\ to\ 01\ June\ 2019.mp4

man mpv
Quote
  --speed=<0.01-100>
              Slow down or speed up playback by the factor given as parameter.

              If --audio-pitch-correction (on by default) is used, playing with a speed higher than normal automatically inserts the scaletempo audio filter.
     

I am in awe  - thanks A-Team

Title: Re: Test space
Post by: A-Team on June 06, 2019, 06:11:54 PM
Testing benefits hereto masking open water in late summer and early fall Ascats. It does seem that features visible today can be seen as early as 17 Sep 2018. This allows monthly measurements of displacement over the 260 days that have elapsed since.

The feature in the animation has largely moved along a meridian to the north pole and sped up this spring. However even at this rate, it would not be halfway to the Fram for another 5 months (early November) and not be exported until April of 2020.

In recent days, ice motion on the Atlantic side has changed somewhat in direction, with Kara Sea ice now entering the CAB whereas for the eight previous months it was being exported (inconsequentially for the melt season minimum) to the Barents.

Dire predictions are being made for a strong Arctic dipole for the rest of June. This might well come to pass but it does not suffice to determine local surface winds nor the stress applied to sea ice, nor predict that motion. (Conversely, atmospheric pressure gradients cannot be inferred from ice motion beyond generalities.)

The Arctic dipole (high pressure on NA arctic; low pressure on Eurasia) is an alternative to the NAO and annular AO patterns first mentioned in 2006 and blamed for summer 2007 record melt.
It was also the subject of an informative Dec 2009 post at WeatherUnderground:

https://www.wunderground.com/blog/JeffMasters/the-climate-is-changing-the-arctic-dipole-emerges.html

Today we have direct daily observational sea ice motion provided by Osisaf (though no forward prediction). Clear-sky insolation and advected heat only affects ice motion after a substantial  delay. It is the synergy between those and the 800 lb gorilla of this year's wind-driven ice fragmentation and translocation that poses the cataclysmic threat to Arctic sea ice this season.

How does early June 2019 compare to previous years? That proves not to be instructive. Here Ascat imagery did not appear until 01 Aug 2012 so that year is not available. The June 4th images for 2013-2019 are shown in the second animation. They would no doubt benefit from open water masking but there would be no benefit to understanding the remarkable current drift year. (Recall 2017-18 had anti-TransPolar drift completely orthogonal to conventional depictions near the Pole.)

The ice pack is largely broken up into free-standing floes in the Lincoln Sea and north; the western CAA is also being reduced to rubble by the CW rotation of the ice.
Title: Re: Test space
Post by: A-Team on June 07, 2019, 08:21:16 PM
Here I am testing an AI algo for removing passing weather artifacts from a Smos-Smap ice thinness color overlay on Ascat for 66 days beginning April 1st and ending June 5th 2019. Smos-Smap v205 looks like it will be continuing throughout June and maybe the whole summer.

See #27 for a similar overlay ending two weeks earlier; note its original color key survives intact whereas Ascat processing map of sigma-0 is quite complex though original brightness values can still be read if a copy of the original layer is left floating underneath as the cryptic active layer.

https://seaice.uni-bremen.de/data/smos_smap/png/north/2019/

The basic idea is that passing polarization in the atmosphere confuse the satellites more and more as the melt season progresses. This gives rise to rapidly moving artifacts that only last for a few frames. Colors persist and grow outwards from where the ice is genuinely thin. Oddly AMSR2, while having weather artifacts of its own, has them at different places and so can be used to screen Smos-Smap but here one wonders if it is a swath timing issue.

Another approach that helps later in the season is to discard isolated colors in the central basin. Operationally, the contiguous (connected) color picker in Gimp can select the valid thinness fringing the ice pack and near troublesome island polynyas like Wrangell's. At any rate, the second mp4 below had many of the putative artifacts in the original mp4 removed.

However there is always the risk of removing something unusual and newsworthy like a newly healing lead or thin ice at the Pole so it may be better just to view as-is with the understanding improbable isolated colors are likely just passing weather not representing anything in the ice.

Thinning has really accelerated in the last 4-5 days on the Svalbard-FJL line (gif). The beige in Smos-Smap turns to color at 0.5 m and below. In other words, a lot of ice was very thin already, in the 0.5 - 0.7 m range.
Title: Re: Test space
Post by: A-Team on June 09, 2019, 05:28:38 PM
I am testing below for differences between U Bremen's SMOS vs SMOS-SMAP maps for ice thinness. Recall the M in both stands for soil moisture; their data (like Ascat's) has been re-purposed for sea ice. The latter brings in synergistic data from a second satellite to correct and enhance the former.

Since the advent of v205 of SMOS-SMAP, there seems to be no justification for using plain SMOS, other than it has a much longer consistent archive (ie same algo versioning) and a one day  shorter lag-to-archive posting. SMOS is riddled with flash artifacts. Both are observational data that have been vetted in the field, unlike Piomas.

SMOS-SMAP is provided at a vastly better resolution (2.83x), measured as Gimp pixel counts on the (polar stereographic) line between St Lawrence Island in the Bering Sea and Bear Island in the Barents (these are consistently visible in both pure imagery and in archival base maps).

That distance is 4738 km (2558 nm) as measured in WGS84 on Google Earth Pro. Accurate pixel counts are the key to re-sizing images to matching overlays:

satellite      pxl       %      ~km/pxl    ~km^2/pxl
SMOS          397.5    75.815   11.92      5.06
Ascat         524.3   100.000    9.04      6.67
OsiSaf       1075.5   204.711    4.41     13.66
SMOS-SMAP    1146.0   218.577    4.13     14.59
AMSR2        1197.6   228.419    3.96     15.24


Both satellites max out (to beige) in the central Arctic during the freeze season, as the ice pack quickly thickens beyond their 0.5m sensing capability. However, certain peripheral areas do not thicken to this depth at any time during recent winters. Thus SMOS-SMAP provides nuanced data during months when AMSR2, Ascat and WorldView see nothing but ice surface.

It's not possible yet to see how the two thinness maps compare during melt season, nor is it clear what they measure or conflate in summer, the possibilities being ice thinness, melt ponds, rafted ice, refrozen melted snow, slushy floes, liquid cloud water, or artifacts from passing storms.

Rather than throw the baby out with the bathwater (not use in summer), it might be better to take (locationally consistent) SMOS-SMAP colors as the thin or dodgy ice, that ice most vulnerable to melt-out. This interpretation interpret very well with the peripheral location of thinness colors both during fall freeze-up of 2018 and into early June of 2019.

The mp4 below is a 266-day hybrid map showing SMOS from 15 Sep to 31 Dec 2018 concatenated to SMOS-SMAP from 01 Jan to 07 June 2019. I originally made it to 700 pixel width but because the center stays so dark and is so large, it views better at 550 width. While moderately difficult to make, the final product only takes up 4-5 MB at 16-20 fps frame rate.

Note the very rapid expansion of dodgy ice in the last few days in the Beaufort-Chukchi and above the Svalbard-FJL-SZ line.

The freeze/melt cycle is largely a story of peripheral ice freezing, moving with the wind, and then melting to an extent determined by whatever weather summer brought. In most years the sub-central ice pack is not noticeably affected (though in fact multi-year ice is on a disappearing trend).

This year the lower CAB has experienced unusual displacement towards the CAA, Fram and Beaufort arm. The area has been cloudy enough that the main region of thick old ice has rarely been visible in Worldview, though intact ice with brittle healed leads can be seen after enhancement.

The contribution of SMOS-SMAP is thus to the near-miss zone: ice that thinned to 0.5m and below but did not quite melt out (or become visible as low concentration by AMSR2) by end of season. It is likely more informative than sketchy albedo and melt pond products earlier in the season as these do not measure either top or bottom melt.

The last three weeks of Ascat are also showing weather streaking across the scene, sometimes leaving permanent effects on radar brightness (ice near-surface dielectric), both lightning (less polarizable constituents) and darkening (more saline or more liquid).
Title: Re: Test space
Post by: be cause on June 11, 2019, 02:54:33 AM
All I can say A .. I'm in awe !

  I've managed to negotiate double my GB's   now I can revisit your domain as often as I want :)

 thanks for your commitment .. and the humour .. I too shout 'over here !' .. bon noite   b.c.
Title: Re: Test space
Post by: johnm33 on June 11, 2019, 02:51:06 PM
Testing
(https://media.giphy.com/media/gjOq4yQDoURBOrXFz5/giphy.gif)
Title: Re: Test space
Post by: A-Team on June 12, 2019, 01:57:33 AM
Here I am testing the effectiveness of a backwards-running mp4 of the Nares funnel (or spillway), the ice in the Lincoln Sea caught up in its extended surface current (driven by sea level differences) above the Nares Strait.

The movie uses near-daily Sentinel-1 images furnished by DMI from 01 May to 11 June 2019. Be sure to set the movie option to 'loop'.

It would be feasible to extend the mp4 back to 15 Sept 2018 though that would require down-scaling and/or faster frame rates to keep file size manageable. The firehose effect may have pauses deep in winter and not persist the whole time, even though water under the ice does flow down the Nares year round at a "steady sectionally averaged mean of about 0.06 m/s, a volume flux of 0.72 million cubic meters per second" [A Münchow 2008].

Although DMI's interest is the waters around Greenland, the images do go far enough offshore to capture the entire funnel 165 km to the north and east, but not enough past Ellesmere Island to really determine where the exported ice originates (from along the coast or up towards the pole?).

In any event, the ice being lost is some of the thickest and oldest ice left in the Arctic Ocean. This ice sector is seldom directly set in motion by the wind (per Osisaf ice motion vectors) but this season it as been strongly pressed down against the western CAA coast by the persistent CW rotation (that has recently reversed in the Beaufort).

According to WorldView, the funnel had an area of 18,400 sq km on 10 Jun 2019 which is 1/54 of a million sq km. It takes roughly 48 days for the area shown in the funnel to flush. At this pace, some 140,000 sq km per year of ice area would be exported, only a fraction of ice loss via the Fram.

The Terra visual counterparts have quite different properties from Sentinel radar and even from the nominally identical WorldView scenes. The last 4-5 days have seen a peculiar darkening of funnel ice in Sentinel and Ascat radar; it leads to a stained glass look at optical wavelengths after reprocessing for feature-following in Gimp (crop before equalizing).

The large floe off Ellesmere entered the scene 48 days ago. It is losing ice on the margins but still is too big to fit down the strait at 37 km height.

For year-round flows through the Nares and the overall freshened water budget history of the Arctic Ocean, see:

https://journals.ametsoc.org/doi/full/10.1175/JPO-D-15-0093.1
https://journals.ametsoc.org/doi/full/10.1175/2007JCLI1748.1
Title: Re: Test space
Post by: uniquorn on June 12, 2019, 02:32:11 PM
<For year-round flows through the Nares> Thanks for these.
Testing the full size ascat mask from upthread with interferometry, 1 day difference, sep17-jun7. Poor choice of date storage and may possibly be improved further by using amsr2 open water mask. I think there is still some life left in it :)
used -crf 27 option to reduce file size
ffmpeg -i intil.gif -vcodec libx264 -pix_fmt yuv420p -profile:v baseline -level 3 -crf 27 -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" interf4.mp4

@johnm33. I like the moon phase idea
Title: Re: Test space
Post by: A-Team on June 12, 2019, 09:04:41 PM
On grabbing date overlays as in #54, there is an easy way to get control of the background making text easier to read. In ImageJ, if taking dates off (renamed or crop-able) file names:

-- early on, duplicate the stack of initial upload
-- crop it down to 13 x 50 or so
-- select all, fill all with sub-black, eg 10 instead of 0 on [0,255]
-- set text color to white
-- make montage, checks on labels and foreground color
-- slice montage back to new date stack, crop to text with 1-2 pixels of boundary
-- later, when you know final width of imagery, adjust canvas checking 'zero fill' and 'center'
-- set 'paste control' to black as transparent
-- then paste on imagery montage, position dates to suit, click to flatten in.
-- on mp4, the controller defaults to covering dates if on the bottom, have to mouse away.

Life is better in Gimp where a text file of vertical dates in monospaced font can be pasted/rendered in a blank image that is the right pixel multiple for number of layers. This allows both day number (Ascat) and calendar date (everything else) using https://www.epochconverter.com/days/2019. Adjust canvas size and use filmstrip to montage to a floating layer over the imagery montage. There is better control of font color and layer transparency so dates don't jump out too boldly.

It is feasible to do this just once for 2018-19 and crop to the date range of individual projects (attached).  This was a nuisance to make as "AI" insists it knows better than you how dates should be formatted, just like it knows better than you how to drive a car. The CSV starts off like this:

01 01 19   Tue    Day 01   01 01 18   Mon   Day 01
02 01 19   Wed   Day 02   02 01 18   Tue   Day 02
Title: Re: Test space
Post by: A-Team on June 12, 2019, 11:19:45 PM
Here I am testing integration of satellite imagery, almost all of which comes to us in polar stereographic projection, into google earth pro (GEP) which can import and align images but is itself in plate carrée projection.

I drew a polygon in the general shape of remnant old thick ice the CAB next to the CAA and adjusted its vertices to make it a million sq km in area. (GEP is quite good at adjusting boundaries and computing WGS84 lengths, perimeters and areas). This draft polygon was a moderately good fit to the main area of whitish Ascat ice in the same region (animation shows stages of this).

The GEP import 'handle' interface is a nightmare for images of large areas, especially those that include the North Pole. It is essential to know the lat-long coordinates of the corners of the images before importing them.

The attached Ascat is cropped to four corners whose lat,lon can be collected in GEP. If it could be overlaid on the GEP earth and a polygon drawn over it, the area of core remnant ice could be determined under various scenarios. Maybe we could even make Nasa-style ice movie as seen from space by importing a time series of Ascat. However their area is just too big given the differences in projections for importation to work.

Now GDAL is an open source cartographic program that can change projectons on png images (ie warp them), with code that looks something like this (EPSG catalog numbers needed for pc and ps):

Step1) gdal_translate -of Gtiff -a_srs EPSG:4326 pc_map_piece.png pc_map_piece.tiff
Step2) gdalwarp -s_srs EPSG:4326 -t_srs EPSG:3995 pc_map_piece.tiff ps_map_piece.tiff

However, I looked for something easier like a free online tool that would compute areas of polygons on PS gifs given the North Pole center and the bounding edge latitude. However all the offerings involved deep dives into software manuals just to chase down a one-time fixed warp.

PS is conformal and so not equal area but is not really that far off at narrow ranges of high latitude, especially if subtracting two areas. So I looked at just counting pixels within a given selection (~polygon) to see what fraction of the Arctic Basin's pixels they constituted.

Since the latter's area is 7.109 million sq km as drawn in GEP coastlines, the product gives a low tech estimate of the selection's area for each commonly used satellite image (see table in #50).

Three minor points here: the world is not going over to NSIDC's lambert azimuthal equal area projection, few data sources provide necessary geo-referenced Geo2D files that Panoply could recast into any of its 120 stock projections and output as kmz, and the satellite archival services could but won't process raw satellite data directly into GEP format which would greatly improve resolution.

What I really wanted to get at here is a melting season essential: how much of the thick multi-year ice is getting chewed up? The same regions of peripheral ice freeze and thaw each year with weather variation and the Arctic Amplification downward trend but that is largely beside the point which is loss of core MYI ice between pole and CAA.

It is only the attack on older ice that matters in terms of a blowout summer from which the ice would never recover -- a catastrophe for the planetary climate. Unprecedented ice motion so far in 2018-19 has left the ice vulnerable even to an unexceptional weather pattern (warmth, cyclone, waves) that could make a very large dent in the core and even herald the end: older ice has already been advected far from its zones of stability into regions where it will surely melt out or be exported by mid-September.
Title: Re: Test space
Post by: uniquorn on June 12, 2019, 11:32:20 PM
Nice.^
Ran out of time today attempting the open water mask so experimented with a simpler and possibly softer option of amsr2 white to alpha overlaid at 50% over ascat then remasked with the circle. This dulls the ascat weather over water and adds more information from the amsr2 lower concentration. Cheated with the amsr2 date and went from blue to 8bit.
The scaling numbers upthread make it much easier to overlay.
Title: Re: Test space
Post by: A-Team on June 14, 2019, 12:43:00 AM
I need to look around for a avi --> mp4 converter that allows lower image quality -- the 271 day sea ice motion movie below is really pushing it on forum file size. Didn't help that much to go grayscale or faster fps, it seems like number of days is the real driver. Doesn't really work here to skip every other day.

Note Osisaf is good on both open and dodgy ice in addtion to its sea ice motion vectors. The netCDF files are in an open archive and Panoply has a five minute walk-through tutorial on how to make vectors from such files.

https://disc.gsfc.nasa.gov/information/howto?title=How%20to%20Create%20Wind%20Vector%20Plots%20with%20Panoply

Note the near-complete absence of Beaufort Gyre ice circulation the last nine months. Magenta near the pole represents persistent pole hole uncertainty. Lots of other things here to see if you set on loop.

Keep in mind, Osisaf is the real thing, not guesswork or weak proxy like sea level pressure or 2m winds. The latter are just models, not observed and not factually grounded since there are no instruments anywhere in the 7,109,000 sq km of Arctic Ocean. Osisaf is taken directly from daily radar fly-overs.

The ice motion vectors are displayed like airport runway wind roses in the bottom image. The Beaufort has the strongest winds blowing ice west off the Alaskan coast. There is also a consistent CW rotation off Siberia that continues to the Fram. The CAB off the CAA sees very little wind and very little ice motion.

That transparency ^ is a nice touch, mellows the colors. Note AMSR2 has a fair number of transient artifacts (diffuse middle blues) in the middle of the pack that need suppression. AMSR2 actually makes very little use of its 100-color palette: open water blue + 100% concentration white make up a huge percentage.

You cannot reduce to say 5 or 10 colors by posterization as the palette is non-linear; however that is easily done manually with the color wand radius on a palette in the montage. Here you can set the Gimp color wand to radius 30, click on the bluest blue and it will highlight everything below 15%, similarly with white 255. I do this on the montage to process all the day layers simultaneously, then replace colors and re-slice.

I've been wanting to reduce these AMSR2 to three colors (low, high, all the rest), then overlay all but the open water with SMOS-SNAP thinness (which has to be a hybrid with SMOS rfi for dates prior to 01 Jan 19).

Circular and elliptical masks not only cut down on distracting off-topic regions but also significantly reduce file size because mp4 compression is 3D and would pick up on the z constancy whatever the frame rate. Thus a circle of radius 1 has area 3.1415 but its bounding square 2x2 has area 4, so there’s a 21.5% savings in file size, eg 4 mb instead of 5. Gimp provides good control over ellipses so once a bounding box is drawn, the ratio of sides can be used to draw the ellipse inside.

Gimp has a really quick way to make multiple copies of a single file and montage it horizontally to a masking layer: simply hold down command-shift-D and watch the layer count grow in the title bar. If you overshoot, command-Z undo to the right number. Then hit ‘filmstrip’ with all its features shut off. Picking a color or transparency with the non-contiguous color wand then lets you fill or otherwise transfer the mask to layers above or below, for example drop a circular mask.

Ascats have a number of programmatic peculiarities: the use of 1 for black instead of 0, poor placement of the sigma-zero brightness palette (which is useless as it is just standard 256 grayscale gradient) an over-contrasted small rectangle off the upper right hand corner of the pole hole that they at first denied though later admitted to but refused to fix (a 95% brightness squeeze is all it needs), an 1170 x 1170 size for an image really of dimension 1153 x 1153 according to ‘zealous crop’ (which is good because odd numbers are essential to have a single pixel define the North Pole namely 577,577 in the cropped or 585,585 in the original.

Note the 9 x 9 pole hole is off-center at 576,576 and incorrectly dithered. It would have been better had they used a white dot or cross-hairs like AMSR2, indicated the meridional termini, specified the bounding latitude and EPSG, and provided an accurate land mask. Had a few basic cartographic parameters like radial pixls per degree of latitude, precise alignment with other satelllite data sources could be immediately automated.

There are a fair number of defective or missing files in the satellite archives. This doesn’t matter too much in a single time series but in multi-source overlays it does. There needs to be 271 files between 15 Sept 2018 and 12 June 2019 in each layer or there will be mismatches of days.. For missing dates, I simply duplicate the earlier date and give it a faux file name. If two consecutive dates are missing, I duplicate the later date for the second.

To repair a file with some missing data (typically a black polygon), I layer it over the preceding date, select and delete its missing data which lets the earlier data show through, then use ‘make new layer from visible’ in Gimp and replace the original defective file with it.

Ascat defectives:

2018 338.gif
2019 005.gif
2019 006.gif
2019 007.gif
2019 044.gif
2019 045.gif
2019 059.gif
2019 068.gif
2019 069.gif
2019 070.gif
2019 147.gif

AMSR2 defectives:

Arc_20181216_res3.125.png
Arc_20190127_res3.125.png
Arc_20190222_res3.125.png
Arc_20190316_res3.125.png
Arc_20190318_res3.125.png

SMOS-SMAP defectives:

2019 04 19.png
2019 04 20.png
2019 04 21.png
2019 06 08.png

SMOS defectives:
none

Osisaf defectives:
none

Sentinel-1 DMI:
1-2 per week
Title: Re: Test space
Post by: sidd on June 14, 2019, 06:54:12 AM
Re: avi --> mp4

ffmpeg ?

sidd
Title: Re: Test space
Post by: A-Team on June 14, 2019, 08:00:48 AM
>> avi --> mp4  ffmpeg ?

Correct, sidd. Some people above are doing command line. However there are dozens of point and click web conversion front ends, all of which i would guess are just ffmpeg under the hood. The better sites presumably implement the most useful commands in ffmpeg.

We may need to go to thumbnails on these forums with outside links to real files on the cloud. Since not everyone has an account there, the question becomes one site with a shared password. However that might encounter vandalism, non-forum use, or site policy issues.

As we go to longer time series, the files become far too big for gifs. I'm concerned that we are hitting the wall with mp4s too as we try to do whole years. I find the mp4s don't load that consistently now which may be an aspect of forum software rather than internet connection.

I have much nicer versions on my desktop than anything I can distribute in a post. A single forum page can really become unwieldy with 30 posts, each of which might have 2-3 mp4s or big images. And what is the point if they are just looking on a phone screen?

With 4-5 overlays, the serious mp4 providers are manipulating a couple thousand individual files. Those can really drag on performance before they can be cropped and resized. Algos that were fast enough before don't scale well with load. The slightest keyboard carelessness can trigger long cpu hang-ups. The new March 2019 iMacs are no faster really than the 2014's.

However there are workarounds. I think we need to start with where we need to be on the science side and then figure out how to get there, without compromising the data but maintaining some level of practicality and accessibility.

Attached is just a nice WorldView png of Wrangel and the ESS that butts up against forum width constraints, a related issue with mp4s that want 720 pixels width.
Title: Re: Test space
Post by: sidd on June 14, 2019, 09:25:34 AM
Some people on this forum have access to pretty serious hardware. But diskspace is a big issue. I see archival becoming a problem already, even with mp4 compression.

Bandwidth is quite cheap, at least if we limit to the users of this forum, but that might be an issue if access is made public. coralcache might be a solution for bandwidth.

Anyone know inside contacts at ESA or panagea ? they might be willing to provide public access archival. I shall ask around the US GFDL and NOAA and edu sites where i know some people. Someone might be willing to donate disk at least, if not too much bandwidth.

I know that microsoft, google, and amazon have discounted or free programs for science. But i hate relying on commercial entity.

archive.org is another possibility.

sidd
Title: Re: Test space
Post by: A-Team on June 15, 2019, 01:13:14 AM
Thx for looking into this, Sidd. It would be great if we could get institutional space somewhere since we are simply reworking and crediting their open source archival graphical material.

NASA SVS has posting very advanced Arctic visualizations for years. They have a real doozy out now that has to be seen to be believed. I am testing various adaptations of it that might work for Arctic sea ice, though there's a tradeoff between eye-catching glitz and actually conveying information.

Climate science journals all refuse to carry gifs, even the arXiv pre-print server won't. Talking here about a ubiquitous graphics standard adopted in 1989. Some do allow .mov but those must be in Supplemental and are not peer-reviewed. Notably, even 'online only' journals still expect you to print a pdf! So there is no distribution outlet there.

http://svs.gsfc.nasa.gov/30701 eight active layers inside a beachball!

Slice 1: Sea Surface Currents & Temperature (ECCO2 model)
Slice 2: Winds (GEOS-5 model)
Slice 3: Precipitable Water (GEOS-5 model)
Slice 4: Clouds (GEOS-5 model)
Slice 5: Precipitation (IMERG data)
Slice 6: Soil Moisture (SMAP data)
Slice 7: Biosphere (Multiple satellite datasets)
Slice 8: Blue Marble (MODIS data)

Meanwhile back at the melt season wx forum, some remarkable happenings are being overlooked, possibly because they are merely observed and not predicted by the alternative reality provided by models.

-- The Nares Strait won't by blocked by the large floe along Ellesmere; it is weeks away and already cracking up according to optical and radar imagery.

-- The disintegration of old thick ice northeast of Banks Island has accelerated. The region of isolated floes now extends 230 km poleward of the central CAA coast (and possibly farther as clouds are masking the WV view).

-- Ascat has been losing its ability to image features for the last four days, especially in the critical central CAB region. This may be due to melt ponding, moist weather systems, or possibly loss of surface roughness. It may still be possible to track the massive open lead system (cracks). It may also get better if previous weather returns. AMSR2 has not been affected.

-- Smos-Smap is showing massive colors here which cannot plausibly represent ice thinness; however its artifacts seem fewer than Smos alone. Both are showing large scale color development along and well out from the Siberian coast.

-- The last 25 days are shown. These could be posted as a 7MB gif instead of mp4; gifs are more desirable as they capture each day's data in a separate frame. mp4 to gif does not work well at recovering this information.

-- Osisaf was still able to post its gridded sea ice motion vectors without Ascat but with more uncertainty (magenta arrows). I have never been able to locate the other png archives it uses.
Title: Re: Test space
Post by: sidd on June 15, 2019, 06:04:05 AM
One possibility for bandwidth might be bittorrent. a lot of unix distributions use it to distribute entire operating systems and applications.

sidd
Title: Re: Test space
Post by: A-Team on June 17, 2019, 05:40:50 PM
The mp4 tests whether features in Ascat remain trackable into June 2019, with the exception of hopeless and transient situation of off-shore Siberia where melt is too pronounced. However the features that could be followed daily from mid-Sept on disappeared about 6 days ago and what can be followed today is mostly refrozen leads.

However it seems that a week of warm moist weather has passed along because the June 16 (day 167 Ascat) shows an abrupt recovery in feature contrast. It is difficult to optimize enhancement simultaneously over the whole scene without masking regions and re-assembling. Below, the CAB is favored at the expense of the Siberian side.

Set the controller to loop on the mp4. It lacks a back-and-forth mode so the mp4 frames were duplicated, with one copy time-reversed and concatenated to the first. This displays ice motion better. It agrees well with Osisaf day-vectors over this time frame. Osisaf captures the operative pressure gradient (ie wind-ice coupling) far better than wx models.

The ice is moving in sub-patterns now, because the wind pattern is not as persistent and because the ice no longer moves as a cohesive pack. Note how inter-floe areas stretch out as the ice accelerates towards the Fram. The Beaufort is also interesting as near-coastal CAB ice continues to be pulled out, like saltwater taffy, in the direction of the Mackenzie delta. Loss of this older ice is imperative for an end-of-season extreme; otherwise we just see the ups and downs of peripheral ice.

Because of the extraordinary advection of young thinner ice across the northern CAB over the last 9 months, roughly along the prime meridian, ice provenance will have be taken into account by mid-season. The older thicker ice has been massively displaced in the direction of the Fram.

Smos and Smos-Smap can't help but still report ice thinness but that is overlain -- and overwhelmed -- by other factors contributing dielectric. Note the color sequence in the palette is maintained south to north, with the periphery 'thinner'. This does not agree well with melt pond distribution (blueish in WorldView) because a number of other factors contribute to the overall artifact picture, such as ice surface roughness and floe vs open water distribution relative to instrument ground resolution.

Both are passive satellite instruments that do not use altimeters. In winter, they measure the change in stokes parameters as emitted blackbody radiation from the upper cms of ocean water passes through the anisotropic ice above. Like so many hand-me-down Arctic tools, Smos and Smap have been re-purposed from their originalmission design which required a near-polar orbit and so provided accidental coverage of the Arctic Ocean.

Smos and Smap in summer have been wrongly written off in journals. There is still information there if you 'let go' of ice thinness; inter-year comparisons must indicate something (but what?). A glance at the non-beige colors above the CAA (where the ice is entirely >0.5m) shows an interesting correlation with a dramatic shift in Ascat brightness. So it is an interpretive matter of what the colors are telling us.

The gif investigates an overlay of SMOS and high-resolution WV visible on a clear day. Again, it is not clear what visible features on the ice surface correlate with Smos and Smap map colors.
Title: Re: Test space
Post by: uniquorn on June 19, 2019, 10:14:37 PM
The change in smos and ascat is quite similar though probably for different reasons. In my laymans terms ascat reflecting off smoother surface features, smos picking up more moisture?
smos overlaid at 35% transparent. Beige (and the grey land mask for some reason) to alpha, jun1-17, forward and back.
Title: Re: Test space
Post by: A-Team on June 20, 2019, 12:44:49 AM
I have been digging through 20 or so papers on SMOS and SMAP ... usually it is the older papers where someone explains how it all works and what causes conflicts (like rfi that is not supposed to be there at 1.3 GHz but is). We are working orthogonally to the goals of these papers which was ice thinness, initially during fall freeze-up and late winter.

SMOS is not a melt pond tool. If it were, they would be shouting hooray. Elsewhere, over land, it measure moisture in soil. It does not measure moisture per se in ice/snow/re-frozen melt. At 21 cm wavelength, it is greatly affected by an assortment of surface properties, most but not all salinity-related.

The first animation below tests at where SMOS, with 35 x 35 km resolution, might be having problems due to a close mix of open water and ice. Here 6.25 km AMSR2 provides a 100% concentration ice mask to let SMOS peek through unaltered where appropriate, with saturation progressively dimmed elsewhere. The SMOS algo wants solid ice.

The second animation re-palettes SMOS to linear grayscale, in increments of 10 on the (0,255) 8-bit scale. This is better for differencing, say consecutive days, whereas the color palette would make change very difficult to interpret.

The third slide show tests whether similarity nesting of Ascat in SMOS in AMSR2 around the north pole is useful (not so much). This only has application in a situation where either a large pole hole
exists for the data or whether the data there is of meagre interest. Here AMSR2 has only 100% concentration, SMOS has only transient artifacts and pole hole, and Ascat is inherently low resolution meaning it can be displayed at its full small scale.

 The final slides test the usefulness of 'mean beige' on Smos-Smap. The original colors were re-paletted to a linear grayscale in steps of 10 on the (0,255) scale, then averaged over June. The areas that were beige the whole time are outlined in yellow. The bluish slide quantifies the high coloration on the Siberian side, the averaging somewhat accounting for flash artifacts.
Title: Re: Test space
Post by: A-Team on June 20, 2019, 06:31:28 PM
Here I am testing whether multiple data channels help interpret events when presented simultaneously. The first animation shows the last 15 days of WorldView, Ascat, Osisaf and Smos-Smap surrounding large-format AMSR2 of the final day. This would be more effective at 1400 x 1400 but that quadruples the size.

While lift-offs on the western CAA are not unusual (and never have gone anywhere), the current ongoing event has produced an additional coastal rubble field almost halfway across Ellesmere Island. WV for June 20th might be quite interesting but more likely it will just show clouds; Sentinel-1's orbit sees through the clouds but does not take in central Ellesmere very often.

The second animation, which is the last seven days of Ascat alone but over a much larger area of the Arctic basin, is more helpful than the six local views of the situation: large-scale ice pack motion has become uncoupled, with pronounced shear across the central CAB towards the Fram and incipient CCW rotation in the coastal Beaufort. It is this latter that seems responsible for the lift-off, with the Ellesmere section caught between divergent stresses.
Title: Re: Test space
Post by: A-Team on June 20, 2019, 06:52:54 PM
Quick test of interactive two image comparison slider tool: doesn't work (or rather the link works great but does not display directly on forum).

We thus seem reduced to taking successive screenshots as OftD did today on the melt forum (https://forum.arctic-sea-ice.net/index.php/topic,2591.msg207042.html#msg207042)

https://juxtapose.knightlab.com/#make

https://cdn.knightlab.com/libs/juxtapose/latest/embed/index.html?uid=74b25fca-937b-11e9-b9b8-0edaf8f81e27 (https://cdn.knightlab.com/libs/juxtapose/latest/embed/index.html?uid=74b25fca-937b-11e9-b9b8-0edaf8f81e27)

<iframe frameborder="0" class="juxtapose" width="100%" height="2170" src="https://cdn.knightlab.com/libs/juxtapose/latest/embed/index.html?uid=74b25fca-937b-11e9-b9b8-0edaf8f81e27"></iframe> (http://<iframe frameborder="0" class="juxtapose" width="100%" height="2170" src="https://cdn.knightlab.com/libs/juxtapose/latest/embed/index.html?uid=74b25fca-937b-11e9-b9b8-0edaf8f81e27"></iframe>)
Title: Re: Test space
Post by: A-Team on June 21, 2019, 04:45:37 PM
Quote
June 13, 2018
'SMOS isn't easy to correct this time of year nor it it entirely a throw-away.' Better to use SMOS temperature brightness archive in summer as "thickness" is misleading and non linear -- seaice.de [25 years of experience with microwave sea ice satellites!!]
Thx, I didn't know about this resource (Arctic basin emissivity at 21 cm, level 3B from v620 L1C data). Roughly speaking, it is SMOS thinness before its (inapplicable-in-summer) algo is applied. Grid resolution is a decent 12.5 km or half that of small AMSR2.

We are looking on the forum for an interpretable meta-EOF sea ice emissivity product for summer based off cross-correlation of Ascat, AMSR2, WV, Sentinel-1, SMOS-TB, SMOS, SMOS-SMAP, Osisaf, and GFS-FV3/ECMWF wx parameters.

Testing on a small scale, TB data is supplied as daily netCDFs, no pngs. However the geo2D opens properly in Panoply so, remembering to save 'preferences' (bottom of Plot menu) after configuring to taste, it is easy to make and export a long time series of appropriate forum width (king size yields 666 pixel Basin width).

The first slide show compares SMOS, SMOS-SMAP and SMOS-TB for 18 Jun 2019. Note the hottest contours correlate fairly well to nearly-always-beige in the averaged product shown in post #66, 4th figure). Overall, SMOS colors have really settled down after a week of explosive development during mid-June, most bafflingly on the CAA side of the CAB where the ice is still thick and the air still cold.

The second image exploits the relatively large pole hole in SMOS-TB data to drop in a small SMOS-SMAP of the same date. This could just as well been a small Ascat or AMSR2 etc. All the combinations are easily made into time series by stacking properly scaled daily concatenates as Gimp layers. The bounding dates are readily maintained by daily downloads. ImageJ has better tools for compositing (eg retain every 3rd date) and mp4 production.

http://icdc.cen.uni-hamburg.de/1/daten/cryosphere/l3b-smos-tb.html data archive
https://twitter.com/seaice_de sea ice news complimentary to zlabed
https://www.the-cryosphere-discuss.net/tc-2019-110/ latest SMOS paper
https://editor.copernicus.org/index.php/tc-2019-110-RC1.pdf  1st reviewer comments
http://www.iup.uni-bremen.de/iuppage/psa/documents/kaleschke03a.pdf 2003 dissertation
Title: Re: Test space
Post by: A-Team on June 22, 2019, 04:51:41 PM
Quote
TorB asks: are ground resolutions of satellite images adequate for computing accurate extent, area, concentration, and volume in summer, given floes floating in open water/slush?
No. The grid cells are far too big in some forum products relative to the size distribution of floes in summer. Error soars as grid cells begin to depart from the intrinsic scale provided by floe sizes.

I began compiling source grid cell sizes below (as archived or as used in algos). It's unclear which forum would provide the best long term storage -- it's a question that comes up all the time.

Because scale varies with latitude in polar stereographic, I used land-surveyed dimensions of Banks Island in km divided by pixel count to determine scales at its (suitably peripheral) latitude. However the scale WorldView embeds in images is good enough for most purposes. (It is ambiguous at the 1-2% level in not making clear whether just the black or black + white bars represents the indicated distance.)

The attachments show various grids over Beaufort floes at the solstice. Download the gif and decide how you would classify individual grid cells.  A nice grid tool is buried in a menu of Gimp (Filters --> Render --> Pattern --> Grid...).

....     WorldView 2x  662 pxls/BI
....     WorldView 3x  331 pxls/BI
3.125    large AMSR2   156 pxls/BI
6.250    small AMSR2    78 pxls/BI
....     Smos-Smap      76 pxls/BI
....     Osisaf         69 pxls/BI
....     Smos TB king   48 pxls/BI
....     Ascat          31 pxls/BI
....     Smos           26 pxls/BI
....     piomas         21 pxls/BI
....     extent?
....     area?
Title: Re: Test space
Post by: uniquorn on June 23, 2019, 03:34:47 PM
Testing ascat overlaid with osi-saf ice drift with white (and land mask and light blue?) set to transparent. Not quite happy with it but it's a test and the arrow vectors show quite well. jun1-20. Judging from windy ecmwf forecast it looks like another cyclone coming up over the beaufort putting the brakes on the gyre  ;) . Works better enlarged. Scaling is approximate.
Title: Re: Test space
Post by: A-Team on June 23, 2019, 06:31:16 PM
Here I am testing a time series for the new resource at U Hamburg called SMOS-TB, the temperature brightness intensity of the Arctic at 1.3Ghz (21 cm) as passively emitted and detected by the satellite. This does not report thinness but furnishes the primary data processed by that algorithm.

As discussed above in #999, it is provided as a netCDF format best processed into an image by Panoply and then edited in ImageJ and saved first as avi and then as mp4. Some converters require an even number of pixels for width and height, producing duds and do not explaining why.

Each date has its own range of data. As with Mercator Ocean, this gives an ever-changing scale and so an unsatisfactory color progression in a time series. Here I manually fixed the scale for all images to 75-285K as Panoply does not let the range be fixed as a preference. I chose this range based on testing of the first, middle and last dates.

SMOS thinness no longer shows ice thinness into June. It does show something consistently over time, probably related to salinity and surface ice temperature. On the other hand, SMOS-TB represents direct observation of surface emissivity at the given wavelength. Since the pole hole is large, miniature version of SMOS, Osisaf, AMSR2 and Ascat for the same date can be inserted into SMOS-TB.
Title: Re: Test space
Post by: A-Team on June 23, 2019, 07:58:13 PM
Just testing to see whether forum software will display the 4 mp4s side by side. The file is still quite small at 4 mb. This allows simultaneous playing of all the inserts. Requires a 21" screen.
Title: Re: Test space
Post by: b_lumenkraft on June 23, 2019, 08:08:41 PM
Not showing inline for me (Mac, Safari).

Works in Firefox though!
Title: Re: Test space
Post by: uniquorn on June 23, 2019, 11:06:14 PM
Yes, good in firefox. If I stare at them for long enough maybe something will click. Probably the hard drive ;)

Tried again with osisaf overlaid with amsr2 this time, also at 70% with 100% ice(white) set to transparent. (edit: osisaf is still white underneath) Large. reduced file size in ffmpeg with -crf 29 switch. I don't detect degradation till it gets well over 30. mar19-jun20
I think it's better over ascat as there is more to see but maybe amsr2 will be better as the melting season progresses. Recommend full screen (double click)
Title: Re: Test space
Post by: Tor Bejnar on June 23, 2019, 11:58:34 PM
A-Team has posted GIFs (or MP4s) that show moving features over the course of a period of time, sort of like the 3rd image from here (https://forum.arctic-sea-ice.net/index.php/topic,2558.msg200735.html#msg200735).  I find this the most useful manipulation to help my understanding what has been happening, for example, that ESS ice does not get exported to the Atlantic in one year in the 'best' of times, ever.

As a 'short cut', would there be a way of using the automated arrows (concept) to display automated curves (not too many, though) that jerk around, distort, and (often) migrate across the Arctic?
Title: Re: Test space
Post by: A-Team on June 24, 2019, 11:33:14 PM
Quote
ESS ice does not get exported to the Atlantic in one year in the 'best' of times, ever. way 2 display curves that migrate across the Arctic?
Below I test whether it feasible to draw forward floe trajectories across the entire Arctic Basin for an entire year within Ascat, the main issue being the abrupt spring to summer transition in contrast from age-related features to exposed leads, which happened on June 4th (day 155) this year. Recall older colder thicker ice can undergo a brittle fracture over a thousand km, with open leads later refreezing with brinier ice which then give lighter and persistent summer lineations on Ascat.

There are six distinct regions in recent years: the ESS with little net motion, the narrow AK coast and Amundsen Gulf, the Beaufort which receives the fast CW-moving arm of CAB ice and carries it to the edge of the Chukchi and then north, the Chukchi which is influenced by the Bering and whose un-trackable ice melts out early, the CAB above the CAA which rarely experiences significant wind stress, and the Laptev to Fram region of anti-cyclonic transport. There is no ice nursery or gyre in the Beaufort; there has not been one since the epic year 2007.

Open water well north of Svalbard is coming as in past years. Ice has been advecting this way faster than it can melt, even with the Gulf Stream arm (WSC) now surfacing north of Svalbard in Whalers Bay (instead of being 300 m deep) per casts reported in Ivanov 2019.

https://iopscience.iop.org/article/10.1088/1755-1315/231/1/012024/pdf

Had the Polarstern anchored in Sept 2018 to a floe above west-central Siberia (as planned for this fall), their year might have ended in June, either in the Barents, or dashed up on the rocks of eastern Svalbard, or stalled out a few hundred km above the Fram.

I would recommend to them starting closer to the pole at say 165ºE (eastern Laptev), though it is wait-and-see if any solid ice will remain there in the fall. A track-back of all the ice that exited the Fram this year might not put them somewhere they want to be. The tip of the black tongue was the place to be; it's tracked back elsewhere into late August 2018 (where it formed at the freeze-up boundary):

https://forum.arctic-sea-ice.net/index.php/topic,2558.msg201986.html#msg201986

The mp4's begin on March 1st and extend 19 days into the summer season. The two disjoint sets of days have very different requirements for optimal enhancement. There is no perfect answer to blending: manual curation is needed to carry forward features into their new signatures. There can be no assurance that tracking will remain possible into Sept.

The Svalbard mp4 would benefit from AMSR2 masking of open water and lower concentrations of ice. However I left as is because the slightest scaling mismatch would give a misleading outcome.
Title: Re: Test space
Post by: b_lumenkraft on June 25, 2019, 07:38:27 AM
What is causing that hiccup at the end there A-Team?
Title: Re: Test space
Post by: Tor Bejnar on June 25, 2019, 02:12:48 PM
A-Team,
To further B_'s question, can you say more about
Quote
the main issue being the abrupt spring to summer transition in contrast from age-related features to exposed leads, which happened on June 4th (day 155) this year.
?
Title: Re: Test space
Post by: A-Team on June 26, 2019, 12:42:23 AM
Quote
Why are Ascat and SMOS affected in summer?
Testing the common daily observational products for systemic interpretation-altering 'transitions' over the last 24 days since Jun 1st, Ascat, SMOS and SMOS-SMAP are the most affected whereas AMSR2, SMOS-TB, Sentinel-1, Osisaf, and WorldView are not.

Although AMSR2 shows passing fuzzy weather artifacts throughout the spring (1st mp4), it still gets the peripheral concentration right into the summer (and indeed through the summer going by past years). The UH product uses the passive 89 GHz (0.3 cm) channel.

With ASCAT, a real aperture active radar operating at 5.3 GHz (5.7 cm wavelength), the most noticeable changes are darkening of whitish multi-year ice in the CAB, washing out of contrast off Siberia, flashing intensities over open water, and appearance of swath lines over the 24 hour build. You can see those in the archived originals, the enhanced, and the June 24th. These are large format pngs so need a click to open at full size.

With SMOS, a passive radar operating at 1.3 GHz (21 cm wavelength), the output gradually sheds its reliable interpretation as thinness beginning in May; adding SMAP helps some but is not a complete fix. SMOS has not gone completely crazy as it first appears: open water is still accurately detected, colors are still palette-radial, and correlations with shorter wavelength satellites can still be seen.

A number of factors associated with summer weather contribute to change (or even loss) of interpretability, among them melt of snow cover, loss of surface roughness, warming of surface ice, advection of moist warm sea air, rain affecting upward extruded brine channels, localized and variable rfi (radio frequency interference), and so on.

A certain level of weather reanalysis -- to replace dodgy forecasts -- would be very useful. However there is not a single instrument currently deployed on the Arctic Ocean that could validate weather parameters.

Since weather events affect the Arctic Basin unevenly, the explanation of changes has to be region-specific and time-dependent. So a lot of information is at hand but easy answers are not. Here we are not "making animations"  but rather testing various ways of viewing disparate data simultaneously (rather than as static GIS layers).

The way forward, preceding graphically in time series to generate hypotheses, might be to combine various grayscale channels into an RGB or CMYK mp4. In other words, Ascat opens in color but the sigma-zero scale is just a grayscale, SMOS-TB is again a single parameter K, as are AMSR2 concentration % and SMOS 'thinness' cm. (However when they aren't archived as gray or provided as geo2d netCDF, it takes some work to re-palette and re-assemble as RGB.)

I've run out of attachments on this post but will add the 24-day June combinations below as the laggards SMOS-SMAP and SMOS-TB come in tomorrow. 
Title: Re: Test space
Post by: petm on June 26, 2019, 03:59:55 AM
So this is where all the good stuff is buried...   :-X
Title: Re: Test space
Post by: be cause on June 26, 2019, 10:31:29 AM
Hi petm .. you could take a year and peruse A-team and Uniquorn's posts over the last few years .. we have been gifted a great resource .. ASIF's back catalogue of posts .. :)  .. b.c.
Title: Re: Test space
Post by: A-Team on June 26, 2019, 09:38:08 PM
Just testing whether webm (google chrome) offers any advantages over mp4. It does not; Neven would have to add it as an "allowed file type" for it to load as an attachment. Plus it offers nearly the same compression from avi as mp4, 28.6 to 8.3 MB. Gifs are better scientifically because each day's data is preserved as a separate frame whereas these cannot be recovered satisfactorily from mov, mp4, or webm. However the gif here was an unworkable 195 MB before compression to avi.

The first mp4 shows ice movement since October 1st. It is a large file but critical to understanding provenance of ice during summer melt season. The display shows forward in time, followed by backwards in time as grayscale invert (as this is helpful under some circumstances).

This year was very unusual in how much MYI ice passed directly over the pole, even portions of the central CAB. If the Polarstern had anchored on MYI on the edge of the minimum at 160ºE, it would have passed over the pole and be on its way to the Fram (if winds pick up again).
The second small mp4 highlights ice pack passage over the five De Longa islands to the north of Kotolny.

Henrietta actually had a scientific station from 1935-63 but unfortunately does not currently have a weather station (from which insolation and nearby ice thickness could be measured). The occasional plumes made by ice passing around the larger three islands prove that, despite being fixed islands, they do not hinder ice movement significantly.

The five islands are not as far north as Svalbard (northernmost Henrietta is 77º08'); their surface areas and maximal elevations are:

Bennett       75 sq km, 384 m
Zhokhova    40 sq km, 123 m
Henrietta      7 sq km,  312 m
Vilkitskogo    2 sq km,   82 m
Jeannette   0.2 sq km, 351 m
Title: Re: Test space
Post by: A-Team on June 27, 2019, 04:27:21 PM
As the summer melt season progresses, condition become more 'challenging' for Ascat image enhancement. This is due in part to advection of warm moist air from lower latitudes but also to surface warming of ice and effects induced by ever-increasing open water.

The slide show begins its test with the original June 26th Ascat which no longer distinguishes open water from ice in the Beaufort, Chukchi and Barents much less exhibits trackable features. The second slide remedies this by masking with 44.10% rescaled UH AMSR2 of the same date and linearly expanding contrast.

The third slide applies 'unsharp mask' within Gimp which is more effective in this image than adaptive contrast sharpening in ImageJ.

The fourth slide adds an overlay of ice motion vectors from Osisaf. These are 3x the size of the actual displacement and represent two days ending on the 26th.

SMOS and SMOS-TB could also be overlaid but their colors overwhelm other data. They need to be converted to grayscale and combined with Ascat as RGB channels. SMOS-SMAP seems to have ceased archiving on June 19th.

While this product is a good way to start the day, multiple days can be stored within ImageJ in its 4D format (and possibly shared through tif which the forum doesn't currently support). The idea of 4D is the ocean area provides 2D, time 1D, and 'depth' or 'z' 1D (meaning how far down in the layer stack). Thus an appropriate animation can be played at any depth.

It remains to be seen whether the decline in Ascat usefulness is a temporary condition attributable to passing weather conditions or a downward trend.
Title: Re: Test space
Post by: A-Team on June 28, 2019, 06:51:38 PM
Here I tested whether it helped to mark the position attained by the ice edge at the Sept 2018 minimum as of June 1st 2019 in terms of tracking ice motion after the Ascat transition. There has been some net motion to the Fram and a lot towards the southern Beaufort though most of the CAB is not going anywhere.

In view of the non-stop nonsense on the melt season forum's 100+ posts a day, I would recommend sticking with ice observables, forgetting these asinine predictions that will never avert anything, nor see follow-up, nor manifest themselves observably until six weeks hence, and instead starting each day by looking at the latest Osisaf ice motion and AMSR2 3.215 sea ice concentration. Those are the only direct and dependable daily tools for seeing how weather actually is coupling to the ice. 

The very first thing to learn about sea ice: its motion cannot be predicted from atmospheric pressure nor from its surface wind prediction. Why look 5-10 days out when it is already wrong at D0?

http://osisaf.met.no/p/osisaf_hlprod_qlook.php?year=2019&month=06&day=26&action=Today&prod=LR-Drift&area=NH&size=100%25

If NSIDC says is impossible to predict the minimum (despite centuries of cumulative staff experience), why do people here who struggle with high school maths feel they are smarter? The word 'skill' has a technical meaning in wx prediction evaluation: outperforming the de-trended recent past, taking error bars into consideration.

Thus what value is predicted ice thickness of 2.0 m if the error is 1.0 m? Ditto extent when error bars envelope the last 10 years of minima? Zero skill, can hardly go wrong. Claimed skills canot even be evaluated.

A surge of weather came up the Fram and added a noticeable artifact to Ascat off Svalbard on June 21st. This timing best fit relative humidity on GFS-nullschool, with no evident correlation to any of its other weather parameters such as total cloud water. The culprit may be something tied to RH such as rain which, if it froze on impact and smoothed a rough ice surface, would indeed affect microwave returns. Note the Ascat artifact is transient, suggesting RH itself could provide a contemporaneous grayscale correction mask.

Try watching the first mp4 at full screen (from a distance). Or download and view in ImageJ where there are far superior controls over speed and re-sizing.
Title: Re: Test space
Post by: uniquorn on June 28, 2019, 11:34:07 PM
Great in full screen though I prefer some repeat final frames to give the eyes a rest. mp4 doesn't load in imagej and no real need to convert back. Enjoying the weather effects on ascat I looked at the fram area 2x, 41,255 contrast, 127,8.3 clahe and unsharp mask 2,0.4, day160-178. Blocky but somehow instructive for me. gif is over 3MB though and probably not worth posting.
Where would one find an RH mask?
Title: Re: Test space
Post by: A-Team on June 29, 2019, 02:58:45 AM
Better if I had said, just double-click on the downloaded mp4 and it will open in QuickTime (on a Mac at least). Then just drag on LR corner and the .mov will expand to your full screen size or anywhere in between. On longer mp4, the double arrows will give double speed (on the way to re-wind).

Could also convert mp4 to gif at a free converter, not always a satisfactory outcome. Tif does a nicer job of saving time series out of ImageJ as frames than gif but files are too large (unless we go to open cloud storage) but I wonder about the shelf life of some of these products as the season goes on.

I've gone back and forth on extra copies of the final frame and if so, how many. ImageJ has a back-and-forth option as well as whatever fps you want (0.1 to 1000, right-click on LR start arrow). It also has manual back-and-forth mousing like QT.

Those are interesting settings you use on unsharp mask. I don't know of an objective way to optimally set the radius and amount.
Title: Re: Test space
Post by: uniquorn on June 29, 2019, 10:44:34 AM
Apart from your recommendations nearly all my settings are subjective. No discipline :)
edit: default unsharp mask does seem more effective than clahe at the moment.
Any chance you have time for this year's ascat ice provenance map or a quick step by step so I can replicate it? I think a series back to 2011 might be interesting.
Title: Re: Test space
Post by: A-Team on June 29, 2019, 04:26:10 PM
Quote
a series back to 2011 might be interesting.
Somewhere back in spring 2018(?), I made a simultaneous animation of nine years of sea ice motion. It had the layout shown below. The current year got the big square and interesting years the four secondaries, with less interesting years the four tertiaries.

Today we have mp4 support and improved enhancement so I wouldn't work within earlier file size and dimensional constraints. ImageJ has a great feature in 'duplication' for taking every nth day which still works very well for motion at n in 3-5 range, meaning a 50 MB mp4 can be reduced to forum limits. Summers have to processed separately or omitted.

Ice motion has really picked up the last two days. It vaguely resembles Beaufort Gyre and TransPolar Drift except that ice is headed dispersively towards the MacKenzie Delta rather than circling and is slamming down on Morris Jesup more than exiting the Fram Strain.

The west central CAB is caught in the middle and has a stationary region (rocker gif) that in part explains its long-term persistence. The eastern CAB is shearing down an old lead towards the Fram. If this pattern persists, a sub-million sq km area of ice will remain in late September.

Ice provenance: one attractive option is tracking the boundary between the Sept minimum and newly formed ice in the fall. This boundary is easy to follow within Ascat and is shown above for early June. Earlier mp4s above show its position in mid-October.

The MYI ice is then pushed ahead of the 'diagonally' moving boundary that is mixed zonal and meridional in character. It has piled up against Svalbard and Lincoln Sea/Greenland in addition to exiting the Fram.

I would not expect much over-rafting of floes at these thicknesses; the lack of concentration deficit does not allow compaction; ridging occurs but has a small areal effect. Ice is not a viscous deformable plastic though it can be effectively modeled as if it were.
Title: Re: Test space
Post by: uniquorn on June 29, 2019, 04:53:31 PM
provenance - I was thinking of this one. A great resource over the last year.
Title: Re: Test space
Post by: A-Team on June 29, 2019, 05:48:21 PM
Yeah, that was a good one. Summary is easier to grok than scientific over-kill.

The last couple of days of AMSR2 are rather concerning (but let's see what tomorrow will bring!). I simplified a montage by replace open water blue out to a radius of 10, same for 100% concentration, then consolidated all the intermediate blues into a single color.
Title: Re: Test space
Post by: A-Team on July 01, 2019, 07:44:32 PM
This will be my last forum post unless something decisive is done about the trolling, stupidity, chat, and trash that are overwhelming the main melt season forum. Page after page after page of complete crap, eg 32 moronic posts in a single day by one completely clueless phony.

I do not want my posts flanked on all sides by this type of degrading material, who does? A lot of very knowledgable people here and many excellent posts but the ratio has dropped to 1:20 on the main forum. Too much to wade through.

And that is by design: a dire melt season --> extra trolls are hired to keep the swamp filled.

We need to do something very differently to get the main forum to work. For instance, allow the crap to continue unabated on side forums but promote worthwhile posts to a restricted-access forum. The worst jerks need to be put on ice until after melt season, minimally.

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

At any rate, the expandable thumbnail below tests whether Arctic Basin bathymetry lines (0, 30, 100, 300, 1000 meters) vis-a-vis salinity have any explanatory power for melt season. Mercator Ocean unfortunately does not provide the key 150 m contour often taken as the continental shelf break in the Arctic.

The bathymetric contours show the extreme asymmetry of shallow water distribution (ie Beringia) favoring the Siberian side. The CAA and AK coasts have very narrow shelves and so little explanatory power for the June 30th ice data columns (AMSR2 concentration, Osisaf sea ice motion, Ascat ice age).

While warming waters there have potentially catastrophic implications for the frozen lid capping already-released methane underground, early melt there probably has more to do with advection of Siberian land heat, clear skies (resp. favorable cloud cover) and horrifically encroaching atlantification than with depth per se.

We've been wondering for months when the Svalbard-FJL is going to open up. It's late because ice motion this year has brought ice in at a sharper meridional angle than in past (ie traditional zonal TransPolar Drift.

V Ivanov 2019 provides an excellent distillation of recent decades of oceanographic research north and east of Svalbard, ie the Nansen Basin (as the bathymetric shelf is minimal offshore as shown).

A great deal of sincere but erroneous and dated information is being posted on the forums so it is worthwhile quoting the highlights here:

https://iopscience.iop.org/article/10.1088/1755-1315/231/1/012024/pdf free full text, no excuses

Atlantic Water (AW) is the major advective heat source which substantially makes up the Arctic Ocean heat budget. The temperature increase in the AW branch entering the Arctic Ocean through the Fram Strait has been observed since in 1990s. The first warming pulse with a temperature peak about 1°C above the climate norm of 1950-1990 was documented in mid-1990s. After a short term cooling, a stronger pulse (up to 1.75°C above climate norm) occurred in the mid-2000s.

Later on, the AW temperature permanently remained within the range of .5 – 1.5°C above the climate norm.

A steady shift to the warmer state of the AW inflow disturbed the existing balance at the lower ice surface due to the increased heat flux from below . According to estimations by,an increase in the average vertical heat flux from the AW from conventional 2 W/m2 to 4 W/m2 would be enough to provide the observed thinning of the Arctic sea ice in the 2000s.

However, it is important to underline that the higher temperature of the AW layer does not guarantee increased heat impact on the sea ice, because almost everywhere in the Arctic Ocean the AW is isolated from the ocean surface and sea ice by high gradient transition layers. In this sense, the western nansen basin (WNB) is a very specific region, because at its western margin the AW reaches the ocean surface.

In ice covered seas, ocean-air heat loss is predominantly compensated by ice growth, release of brine into the water, and subsequent density increase. However, over most of the Arctic Ocean, the depth of haline convection is limited to a few tens of meters since the amount of brine released from the growing ice is insufficient to make the water dense enough for mixing up the underlying pycnocline. With the increasing seasonality of Arctic sea ice cover, this steady regime is changing and the most noticeable change occurs along the AW flow in the Nansen Basin.

The reduction of pan Arctic sea ice cover initiated a positive feedback loop connecting the change of vertical thermohaline structure with regional ice decay in the Western Nansen Basin, where eastward-moving warm Atlantic Water collides with sea ice drifting out from the central basin.

This collision results in AW cooling and freshening in its surfaced upper part due to ice melt. Under these conditions, a compact region north of Svalbard (the so-called Whalers Bay) remained permanently ice free in winter because of steady sensible heat polynya, maintained by the AW heat.

In the changing climate, the Arctic sea ice cover shrinks down and the share of seasonal ice increases while the ice itself becomes more thin, mobile and fragile. These changes on the pan-Arctic scale invoked regional response, namely reduced ice import to the marginal transition zones (seas) from the central basin.

In case of the WNB, breaking of earlier existed steady-state heat and salt balances in the upper mixed layer (UML), together with an increased heat and salt import with the AW inflow, reduced vertical density stratification, thus facilitating development of winter thermohaline convection along the AW pathway.

Enhanced convection delivers additional heat and salt to the UML contributing to accelerated sea ice melt and/or impeding local ice formation. The strong seasonal cycle of temperature in the AW layer with the culmination at the mid-WNB meridian in early winter additionally facilitates convection development above the AW warm core. Satellite detectable outcome of this chain of events is an anomalously long duration of low ice concentration zone in the WNB in mid-winter, which is observed after 2012.

The currently observed decrease of ice area in the Barents Sea was preconditioned by the reduction of ice import from the central basin in the 1990-2000s. Consequent weakening of density stratification enhanced vertical mixing down to intermediate Atlantic origin water (AW). Excessive heat input from the AW to the upper mixed layer (UML) led to further reduction of sea ice, thus closing the positive feedback loop.
Title: Re: Test space
Post by: oren on July 01, 2019, 09:12:34 PM
I sincerely hope that you will keep on posting, at least in this disruption-free thread. I'll take quality over quantity any time.
Title: Re: Test space
Post by: uniquorn on July 02, 2019, 12:11:23 AM
It will be a wrench but I'm heading the same way.
There's gardening to be done.
Title: Re: Test space
Post by: HapHazard on July 02, 2019, 12:28:55 AM
This will be my last forum post unless something decisive is done about the trolling, stupidity, chat, and trash that are overwhelming the main melt season forum. Page after page after page of complete crap, eg 32 moronic posts in a single day by one completely clueless phony.

I do not want my posts flanked on all sides by this type of degrading material, who does? A lot of very knowledgable people here and many excellent posts but the ratio has dropped to 1:20 on the main forum. Too much to wade through.

And that is by design: a dire melt season --> extra trolls are hired to keep the swamp filled.

We need to do something very differently to get the main forum to work. For instance, allow the crap to continue unabated on side forums but promote worthwhile posts to a restricted-access forum. The worst jerks need to be put on ice until after melt season, minimally.


Amen to that.
Title: Re: Test space
Post by: magnamentis on July 02, 2019, 02:00:17 AM
i know the following won't make me loved but i shall always express my convictions and/or
knowledge despite the outcome. Analyzing humans, their behaviour as well as their motivation that is none of the most important factors long term, as well and pull them back up above the surface
has been my work for almost 60 years now, hence:

feel free to stay away i'd say because:

- blackmailing is one of the worst and most moronic attitudes ever

- nobody is indispensable

- whining and complaining while being most respected and having a place almost for one alone
.  is cheap IMO

- arrogance is one main culprit for many disasters, haughtiness comes before the event

- this is how the wrong people come to power and i'd rather learn to do things myself than
. depend on one of them.

- last but not least it's really easy to produce all the stuff, what it takes is time and minimum .
. photoshop skills
Title: Re: Test space
Post by: oren on July 02, 2019, 02:46:38 AM
i know the following won't make me loved
No it didn't. In fact you've just made me angry. The level of analysis and imaging displayed in this thread is astounding. "Really easy to produce", obviously you've never tried. I have - nearly impossible - couldn't even manage to follow the included instructions - way above my level. One should recognize and acknowledge quality when one sees it.
I will not continue this here, as this was one of the only quiet and disruption-free threads on the forum.
Title: Re: Test space
Post by: petm on July 02, 2019, 05:15:06 AM
This makes me very sad. I will stop posting completely then, as I feel I am part of what is described. Don't go, A-Team.
Title: Re: Test space
Post by: Rod on July 02, 2019, 05:39:47 AM
This makes me very sad. I will stop posting completely then, as I feel I am part of what is described. Don't go, A-Team.

If you stop posting the bad guys win.  That is why I’m so pissed at A-team for attacking these forums. 

These forums are important.  You are an important poster.  Please keep doing what you do.  People are watching!

Hyperbole and BS are not important.  But, many people on these forums contribute real world data that is lacking on other platforms. 

You are one of them. 
 
Title: Re: Test space
Post by: be cause on July 03, 2019, 12:43:00 AM
well .. we are rid of the troublemakers .. Uniquorn and A-team ...
Title: Re: Test space
Post by: Sterks on July 03, 2019, 01:23:11 AM
Another dramatic exit by our most revered scientist.
Neven, this forum is yours, but I personally find very strange that:
- A member demands other members to be expelled en masse, otherwise he's gone. He can be the pope of Math & Physics, I don't care, he does not have the right, or he should not. And anyway, if he doesn't like the forum he could create one of his own.
- A thread may be created with exclusivity, invitations, privilege (well, he invaded the Test Space and stayed there with almost exclusivity, nobody was bothering His Majesty). What is that, like an Internet of two speeds, one for Royalty and another for the vulgars?
- The melting season thread is just fine, if there weren't so many triggers (people respond less to comments they don't like, including me), and yes, Neven talks to a couple of members. But, except for the triggering, I feel things are going relatively fine.

I profoundly dislike A-Team, now that he went public with the drama and explicitly demanded people be expelled. He is an elitist and almost everything is shit for him. Well DEAL WITH IT, if you have IQ 160 you have to learn to live with 99.73% more idiots than you. Yes I love his contributions, but lately I even forgot the damn Test Space. And Uniquorn is just as brilliant (if not the same person), and a nice member.
Title: Re: Test space
Post by: SteveMDFP on July 03, 2019, 02:03:47 PM
I profoundly dislike A-Team, now that he went public with the drama and explicitly demanded people be expelled. He is an elitist and almost everything is shit for him. Well DEAL WITH IT, if you have IQ 160 you have to learn to live with 99.73% more idiots than you. 

There is zero value in commenting on other members.
This is generally a science-based forum.  Science isn't a democracy, it's a meritocracy.  Meritocracy only looks like elitism to those who don't appreciate talent and ability.
Most of us would put up with a lot of distasteful behavior from an Einstein, while being intolerant of the same from Joe Blow. 
Title: Re: Test space
Post by: be cause on July 03, 2019, 02:48:28 PM
 ^^^ +1 .. thanks Steve .. b.c.
Title: Re: Test space
Post by: Sterks on July 03, 2019, 03:38:25 PM
I profoundly dislike A-Team, now that he went public with the drama and explicitly demanded people be expelled. He is an elitist and almost everything is shit for him. Well DEAL WITH IT, if you have IQ 160 you have to learn to live with 99.73% more idiots than you. 

There is zero value in commenting on other members.
This is generally a science-based forum.  Science isn't a democracy, it's a meritocracy.  Meritocracy only looks like elitism to those who don't appreciate talent and ability.
Most of us would put up with a lot of distasteful behavior from an Einstein, while being intolerant of the same from Joe Blow.
Tell that there is zero value in whining to A-Team, in wanting to remove all the plebs, and tell to yourself that there are very few scientists around here. Tell to yourself that this is not a scientific conference though the members should respect science as AGW and ASI loss are rooted in science.  Finally my point of view is that if Einstein comes and tells remove everybody I dislike from a public forum, this is My Space, I would tell him to suck it.
BTW We are off topic here, I guess, if replies, we can go to the other thread, Forum Decorum
Title: Re: Test space
Post by: uniquorn on July 04, 2019, 12:52:45 PM
Here testing osisaf overlaid onto worldview aqua modis at 50% with nearly all background set to transparent, attempting to show only the arrows. Some artifacts remain. I haven't worked out how to get the vectors from the .nc files :(
Osisaf is showing drift from the previous 2 days in this configuration, jun25-27-jul1-3
maybe should have applied contrast to wv first
Title: Re: Test space
Post by: uniquorn on July 04, 2019, 01:22:51 PM
Worldview looks better but the artifacts spoil it when zoomed in on an area of current interest. large gif, but this is a test thread. click to run.
btw, tis too hot for gardening right now
Probably should match the worldview dates to the mid osisaf date next time.
Title: Re: Test space
Post by: uniquorn on July 05, 2019, 07:44:19 PM
testing size, won't be up for long
Title: Re: Test space
Post by: b_lumenkraft on July 05, 2019, 07:51:15 PM
Wow, that's awesome Uniquorn.

Makes it pretty clear the melt on the Pacific side is mainly driven by Pacific waters coming in, no?

(glad i grabbed it soon enough! ;) )
Title: Re: Test space
Post by: uniquorn on July 13, 2019, 12:26:33 PM
Testing unihamburg amsr2-uhh, caa coast, 2013-2019. Many errors, no corrections, no dates, missing data, probably won't bother to do it again. Low quality to reduce file size. Some may find it interesting.
edit:Thanks for the suggestions below oren, but there are too many corrections to make on the amsr2 files. I've removed it as it justs clogs up the thread.
Title: Re: Test space
Post by: oren on July 13, 2019, 12:56:29 PM
Actually very interesting, especially considering the effect the CAA may have on a new record. I am personally less interested in the CAB-CAA crack, which has more of a headline value.
But, it requires at least year labels. I could recognize 2016 by the "garlic press". I note that the CAA changed beahvior after that, filled with MYI and more resilient to movement and melting and clearout. A bit like the old Arctic ocean.
In addition, I would drop 3 months Jan-Mar out of each year, to make it shorter.
That is of course if you plan to ever make another...
Title: Re: Test space
Post by: uniquorn on July 16, 2019, 09:46:57 PM
testing todays nullschool temp/wind badly overlaid onto yesterdays worldview and amsr2
speed is wrong due to reducing file size
obviously ns overlay rotation is wrong too.
removed.
Title: Re: Test space
Post by: FishOutofWater on July 17, 2019, 04:52:40 PM
I sympathize with A-Team's frustration concerning the melting season discussions. Except for Nico Sun's albedo warming potential, which has shown some promise for guiding predictions, there is no skill in September minimum forecasts. To make a skillful forecast it is first necessary to predict weather over a month out. Of course, that's no all that's needed, but because it's impossible to do that all of the September forecasts are at best ways of testing our models and ideas. Generally they are entertainment without scientific content.

There is far too much noise in this year's melting season threads.

I don't blame people with bad intentions, although there have undoubtedly been a few trolls. This place has become popular and people who have little or no content to add get excited and jump in with emotional content. That's human nature, I guess. So this place is a victim of an interesting year and the success of this forum in grabbing a large audience.

There is no easy answer to this problem. Creating a thread for expert posts would cause its own set of problems.
Title: Re: Test space
Post by: uniquorn on July 19, 2019, 05:40:47 PM
Agreed. We just get used to scrolling more.
Here testing large mp4 of unihamburg amsr2uhh jun1-jul18 using ffmpeg -crf 29 which compresses to 2.12MB
Quote
Choose a CRF value. The range of the CRF scale is 0–51, where 0 is lossless, 23 is the default, and 51 is worst quality possible. A lower value generally leads to higher quality, and a subjectively sane range is 17–28
not quite sane then.

Obviously it is intended to be viewed full screen - double click probably. Is it too big for mobiles (portables)?
Title: Re: Test space
Post by: Oscillidous on July 19, 2019, 05:59:27 PM
Your animation can be viewed in Chrome for Android with a bit of scrolling around. I prefer embedded videos so thank you for your efforts.
Title: Re: Test space
Post by: be cause on July 19, 2019, 06:19:25 PM
Cheers Uniquorn .. if only you could provide as clear a view looking forward as you do looking back ! b.c.
Title: Re: Test space
Post by: HapHazard on July 19, 2019, 07:00:58 PM
There is far too much noise in this year's melting season threads.

Understatement.

uniquorn, I love that animation, thanks. Flawless. (desktop, fullscreen, low-ish bandwidth)
Title: Re: Test space
Post by: Tor Bejnar on July 19, 2019, 07:09:37 PM
ditto on loving the movie, except I have lots of bandwith
Title: Re: Test space
Post by: Oscillidous on July 19, 2019, 09:14:07 PM
It's interesting and frightening to imagine that people with an agenda come here to sew discord within the forum. Unfortunately these issues will only worsen the more people who come here.
Title: Re: Test space
Post by: oren on July 20, 2019, 12:20:54 AM
Uniquorn, the animation is superb, having watched it 10 times on the phone, each time focusing on a different region. I recommend posting it as is in the melting season thread.
I must add, the quick complete destruction of the ESS and Laptev fast ice is nothing short of astounding. I just hope the CAA doesn't follow suite, as the south end of Parry Channel started to crumble big time.
Title: Re: Test space
Post by: DrTskoul on July 20, 2019, 12:48:34 AM
As GIF
Title: Re: Test space
Post by: FishOutofWater on July 20, 2019, 05:09:43 AM
The animation was stunning and disturbing. Far more ice has melted in the Beaufort sea than was apparent from looking at single images. It was possible to track large blocks and watch them melt out. What is disturbing is that this was thick ice from the central Arctic and multiyear ice from the CAA. The ice pack is in worse shape than I realized before watching the animation.
Title: Re: Test space
Post by: Wildcatter on July 21, 2019, 09:25:54 AM
Testing AMSR2 last 5 days
Title: Re: Test space
Post by: be cause on July 21, 2019, 11:06:31 AM
Hi wildcatter .. the moving frame of the gif distracts badly from following the detail .. but keep on trucking .. b.c.