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Messages - Wipneus

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1
Antarctica / Re: Latest GIOMAS/PIOMAS volume data for Antarctica
« on: February 12, 2019, 07:31:27 PM »
Animated GIOMAS Antarctic sea ice thickness, the first forty years...

2
Arctic sea ice / Re: Global sea ice area and extent data
« on: February 11, 2019, 04:16:37 PM »
Following the GIOMAS update here are the update volume and volume-anomaly graphs.

3
Antarctica / Re: Latest GIOMAS/PIOMAS volume data for Antarctica
« on: February 11, 2019, 04:12:44 PM »
GIOMAS data has been updated to 2018-12-31.

I have updated most of the graphs, let me know if there is one that I overlooked.

Even better is that daily data is now available. All the graphs are will have to be modified. It is a huge improvement but will take some time as the amount of data is causing performance problems.

The place for these graphs are (arctic and antarctic):
https://sites.google.com/site/arctischepinguin/home/giomas

A few global (NH+SH) are on the global sea ice page:
https://sites.google.com/site/arctischepinguin/home/global-sea-ice

Attached are Antarctic volume and volume-anomaly graphs




4
Arctic sea ice / Re: Latest PIOMAS update (February)
« on: February 11, 2019, 02:56:03 PM »
PIOMAS has released the official volume data up to the end of January. Unfortunately not the daily gridded data that I use for the animation and some other graphs.

Attached are the volume and volume-anomaly graphs. I tried to do something quick about the "reds problem", still not ideal but looks to me a little better.  If someone knows a source with optimum distinguishing colors for a line-style graphic with 20 or so lines...


5
Developers Corner / Re: Test space
« 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

6
Arctic sea ice / Re: Latest PIOMAS update (January)
« on: February 05, 2019, 06:44:45 PM »
Thanks to all that have tried and responded.

The positive feedbacks gives me confidence that I have nailed a big source of the incompatibility. In short: do not create mp4 files with an odd number of rows.

Cropping the image height from 695 to 694 gives the attached "big" animation:

7
Arctic sea ice / Re: Latest PIOMAS update (January)
« on: February 05, 2019, 04:25:12 PM »
Lots of people can see the animation within the forum, some have to download first and some have failed altogether.

On my Linux computer Chrome works fine but Firefox does not recognise the movie. I have uploaded a smaller animation that works fine here with both browsers.

Can people that had difficulties give it a try and report?

The post is here:
https://forum.arctic-sea-ice.net/index.php/topic,2558.msg188194.html#msg188194

8
Developers Corner / Test space
« 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.

9
Arctic sea ice / Re: Latest PIOMAS update (January)
« on: February 05, 2019, 09:32:16 AM »
While waiting for the lastest January data, here is an animation of the full range 1979-2018. Made possible by a recent inclusion of 1979-1999 daily thickness data.

Displayed are thickness data every 5th day to keep the file size relatively limited.

It is coded as an mp4 file, experimental for me, over 13meg in size, see it works for you.


10
Arctic sea ice / Re: Latest PIOMAS update (January)
« on: February 01, 2019, 08:43:41 AM »
Attached the Fram volume export graph. December export below average.

Also updated regional data files:

https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional-monthly.txt.gz
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

I expect a new PIOMAS update is very near, so I postpone the latest thickness-difference maps.

11
Arctic sea ice / Re: Latest PIOMAS update (January)
« on: February 01, 2019, 08:20:19 AM »
Here are the volume and volume-anomaly graphs updated to 2018.

12
Arctic sea ice / Re: Latest PIOMAS update (January)
« on: February 01, 2019, 08:18:45 AM »
PIOMAS has updated to 31st December. Both the volume as the gridded thickness data are available. Volume on 31 december was 15.02 [1000km3], 6th lowest for the day (but nearly as low as  2011: 15.01 [1000km3]).

Here is the animation for December last year:

13
Arctic sea ice / Re: Latest PIOMAS update (mid December update)
« on: December 19, 2018, 09:43:01 AM »
The volume and volume-anomaly graphs are updated (and uploaded). Attached.

No ice velocity data, so no updated Fram export graph.

Daily regional volume data uploaded:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz




14
Arctic sea ice / Re: Latest PIOMAS update (mid December update)
« on: December 19, 2018, 08:51:36 AM »
@Wipneus
It seems you gave the new graphs from beginning of November on to Neven, but not on your arctic penguin page, where the last data is from back then.

Thanks, seems I forgot something. Will update it as soon as the new data has been processed.


15
Arctic sea ice / Re: Latest PIOMAS update (mid December update)
« on: December 19, 2018, 08:40:12 AM »
PIOMAS gridded thickness data has been updated, last date 15 December.
Calculated volume at 15 December was 13.07 [1000 km3], which is 6th lowest for the day.
Here is the animation.

16
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: December 18, 2018, 12:12:41 PM »
JAXA ARCTIC EXTENT 11,820,858 km2(December 17, 2018)

Here is the analysis, even though I am still unsure about the 263k gain on 16 December. The 17 December image is complete, and appears to confirm the sudden gain in extent.

Remember that the ADS/NIPR extent figures are two-day averages. The spike occurred on the 16th,  affecting the 15-16 and 16-17 (reported as 16 and 17 th december data) equally. On the 18th the situation will return to normal (hopefully).

My no-average extent calculation from Jaxa SIC jumped a +1010k on the 16th.

17
Antarctica / Re: Sea Ice Extent around Antarctica
« on: December 12, 2018, 12:46:57 PM »
Two simple questions (they could go in the stupid question thread, but are on topic here):

1) Shouldn't there be some minimum % that compaction can reach if it is a ratio of two measurements that are not independent? I'm trying to make sense of how the compaction data over the last two weeks can be so different from previous years. Clearly it has to do with rate of melt; again, you'd think that area can only get so far ahead.

Theoretical minimum is 0.15, for this to be true the maximum concentration in any gridcell is 15%.  Grid cells with concentration less than 15% are neither counted in the area or the extent totals.

Quote
2) Compared to extent, isn't area the better metric for thinking about albedo?

For albedo yes. Here the calculation of area is actually underestimating the true value of melting ice, whetting the surface causing pools, is actually an advantage because those conditions also cause lowering of the albedo.

Quote
Extent seems like it's faster to calculate, but otherwise has no advantages over area.

Extent is much less sensitive to the melting surface. Historic observations where mostly the position of the ice-edge from which only extent can be estimated. Area measurements are only available in the satellite era.


18
Antarctica / Re: PIG has calved
« on: December 09, 2018, 01:08:46 PM »
Detail of some break-up of the latest (September) Calving in this Sentinel 2B shown in native 10m/pix resolution. The preference for square angles is obvious.

19
Arctic sea ice / Re: Latest PIOMAS update (December)
« on: December 05, 2018, 03:17:32 PM »
I'm intrigued as well. I guess only Wipneus is qualified enough to explain this discrepancy. As far as I know PIOMAS corrects itself using NSIDC concentration data, and I seem to recall it also cuts off at the 15% threshold, but I could be wrong.

Not much help I am afraid. The assimilation used in PIOMAS is described here:
https://doi.org/10.1175/JTECH1871.1

The assimilation of sea ice concentration (from NSIDC) does not mean it is instantly copied into the model, it is more "nudged" to the measured values. Smaller absolute values of concentration are nudged less than larger values.

The influence on volume, probably the most important output of PIOMAS, is likely small. My favorite glitch is the ice on the SW coast of Greenland, sometimes present when temperatures are well above zero.

And no, there are no 15% cut-offs. Not in my graphs, not in those of the PSC (to the best of my knowledge).

20
Arctic sea ice / Re: Latest PIOMAS update (December)
« on: December 04, 2018, 09:28:34 AM »
Thickness map for the 30rd of November, compared with recent years and their diff's.

22
Arctic sea ice / Re: Latest PIOMAS update (December)
« on: December 04, 2018, 09:18:18 AM »
The Fram export graph. During the last few days the export has increased noticeable, which I think is visible in the animation above.

23
Arctic sea ice / Re: Latest PIOMAS update (December)
« on: December 04, 2018, 09:14:05 AM »
Here is the animation for November.

24
Arctic sea ice / Re: Latest PIOMAS update (December)
« on: December 04, 2018, 08:24:05 AM »
PIOMAS data has been updated, both the "official" volume data and graphs as the gridded thickness data.

Volume on 30th November was 11.453 [1000 km3], which is the sixth lowest value for that day.

As I am still downloading the gridded data, we start with the volume and volume-anomaly graphs.

25
Arctic sea ice / Re: Latest PIOMAS update (November mid-monthly update)
« on: November 20, 2018, 09:21:07 AM »
No new Fram export graph, the ice velocity data is missing.

Regional daily volume data updated:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

26
Arctic sea ice / Re: Latest PIOMAS update (December)
« on: November 20, 2018, 09:15:21 AM »
Here are the updated volume and volume-anomaly graphs.

27
Arctic sea ice / Re: Latest PIOMAS update (November mid-monthly update)
« on: November 20, 2018, 08:55:44 AM »
PIOMAS gridded thickness data was updated to the 15th of November. Volume (calculated from thickness) at 15 November is 9.42 [km3], 5th lowest after 2011, 2012, 2016 and 2017.

Here is the animation.

28
Antarctica / Re: PIG has calved
« on: November 19, 2018, 07:04:53 PM »
I posted the first attached image before, here

Second is the same suspected crack pictured by Sentinel 2B, same resolution different orientation. The improved quality still shows not show much more than a dent in the snow.


29
Antarctica / Re: PIG has calved
« on: November 10, 2018, 12:53:10 PM »
Here is that nightly Landsat image from 7 November. It is the same as the NASA image reported some posts above. NASA did succeed to give it a "sunny" look, but the sun's elevation above the horizon is only 1.15 degrees. So I don't mind a more shadowy appearance after some contrast enhancement.

Those shadows bring out more linear features of which the middle one (of three most prominent) is the one I mentioned before.

1400x1400 pixels (15m/pix) : click for that hi-res image.

30
Antarctica / Re: PIG has calved
« on: November 10, 2018, 11:09:17 AM »

Would you mind to combine this photograph with the one you posted on Reply #767 on: September 21, 2018, 09:11:33 AM? Is this the same crack or a new one?

Thanks a lot!

It is the same (suspected) crack. These Landsat images are just able to show the dent in the snow, very much depending on the Sun elevation and direction.

I am downloading a clear Landsat image from 7 November now, which is really a night image so has a low Sun position. See how that shows.

I intent to closely follow any developments of this crack of course, but surprise (to me) calving do happen.

31
Arctic sea ice / Re: What's new in the Arctic ?
« on: November 07, 2018, 05:31:41 PM »
Safe to assume Alberto should be Albedo?
Spell checker mess.

32
Antarctica / Re: PIG has calved
« on: November 07, 2018, 03:18:54 PM »
Landsat delivered a cloud-free image of the PIG and the recent calving, now officially named B-46 (as long as it does not disintegrates into small pieces ). The image is attached at 60m/pix.

The arrow points at a linear feature, that may be the next big crack. This is shown in detail, resized to 7.5m/pix and contrast enhanced.

A cloud-free Sentinel 2 image would be very nice now.

33
Arctic sea ice / Re: What's new in the Arctic ?
« on: November 07, 2018, 09:54:48 AM »
The KNMI (Royal Netherlands Meteorological Institute) issued a small news report (what they call climate-message).

The message is that the decline of Arctic Sea Ice has been mostly in thickness, not area. And that will change when the ice get thinner. The consequence of this is that Arctic warming will amplify as AlbertoAlbedo will drop.

On twitter one of the scientists speculates that Arctic amplification will increase from current 2-3 to future 4-5.

The message is in Dutch, but should be readable with Google translate:

Quote
We need climate models to make the best estimates of future changes in the climate. KNMI plays an important role in the development of a precise global climate model (EC-Earth) with which we can study the consequences of Arctic changes. The model results show that sea-ice retreat will play an increasingly important role in the loss of Arctic sea ice in the future (figure 1). Because this increases the warming of the Arctic relatively strongly (compared to the thinning), the temperature in the Arctic is expected to rise more and more quickly.



Quote
Figure 1. Future simulation of Arctic sea ice thickness (SIT) and sea ice surface (SIA) showing that the sea ice thickness is decreasing nowadays, while in the future the sea ice surface will decrease.

34
Arctic sea ice / Re: Latest PIOMAS update (November)
« on: November 06, 2018, 12:32:52 PM »
Thickness map, compared with previous years and the differences.
What I find most disturbing here is the complete absence of 4M+ ice.  We are inching closer to the end of freeze season volume matching annual heat uptake.

Time to show my PIOMAS thickness distribution. As some may remember, ice in each gridcell in the PIOMAS model is specified as a discrete distribution: there exist 12 categories of ice thickness (m):
[0.00, 0.26, 0.71, 1.46, 2.61, 4.23, 6.39, 9.10, 12.39, 16.24, 20.62, 25.49]
gice specifies the percentage less or equal to the thickness of each category.

The attached graph shows the area of ice that is thicker than each thickness cat.

4m+ ice is indeed declining dramatically,  but that is not a recent development.

35
Arctic sea ice / Re: Latest PIOMAS update (November)
« on: November 04, 2018, 08:38:37 AM »
Thickness map, compared with previous years and the differences.

37
Arctic sea ice / Re: Latest PIOMAS update (November)
« on: November 04, 2018, 08:18:30 AM »
Fram Strait export, still below the long time monthly average (the grey steps in the background).

38
Arctic sea ice / Re: Latest PIOMAS update (November)
« on: November 04, 2018, 08:13:31 AM »
The volume and volume-anomaly graphs show that the ice volume growth is currently similar to 2011.

39
Arctic sea ice / Re: Latest PIOMAS update (November)
« on: November 04, 2018, 07:42:36 AM »
PIOMAS gridded thickness data has updated. While we are still waiting for the "official" volume data, volume calculated from thickness on 31-Oct was 7.23 [1000km3],  fourth lowest behind 2011, 2012 and 2016.

Here is the October animation.

40
Antarctica / Re: PIG has calved
« on: October 29, 2018, 12:10:12 PM »
Yes it calved again. Sentinel 1 images, medium resolution (EW=40m/pix scaled to 80m/pix).

41
Consequences / Re: Global Surface Air Temperatures
« on: October 27, 2018, 08:27:13 AM »
I'm not sure what this means.

It means the European "no warming since 2000" hiatus is over.

Or alternatively it marks the "cooling since 2018" period.

Your choice.

42
Antarctica / Re: PIG has calved
« on: October 26, 2018, 02:33:31 PM »
Thanks a million for this important animation. I wonder whether this is just another major calving event or whether it is the beginning of the complete collapse of the PIIS.

Estimating the shift in 24 days about 32 pixels (@10m/pix in the original Sentinel images), plus or minus 3 pix gives an average speed of 32*10/24=13.3 m/day (range 12.1-14.6).

I started making such estimates 5 years ago when the speed was about 10, gradually climbing through the years to 11, to 12 and now about 13 m/day.

So speed increases slowly, but not a collapse yet.

On the other hand, if the upstream movement of the calving front is the thing to worry about than I'm not so sure.


43
Antarctica / Re: PIG has calved
« on: October 25, 2018, 04:55:12 PM »
Three image (60m/pix) animation, showing the developments in the cracking field.

44
Arctic sea ice / Re: Global sea ice area and extent data
« on: October 23, 2018, 09:15:22 AM »
To my elderly eyes it appears that, in both area and extent, this is likely to be the first time in the satellite record that the autumn local maximum is lower than the summer one. Am I right?


Actually 2016 was the first to do this, and did so for both extent and area.

Actually the first full year in the available series, 1979 was the first. After that no other years until 2016.

Click those attachments for the big view.

45
Arctic sea ice / Re: Latest PIOMAS update (October mid-monthly update)
« on: October 21, 2018, 08:48:59 AM »

46
Arctic sea ice / Re: Latest PIOMAS update (October mid-monthly update)
« on: October 20, 2018, 03:09:02 PM »
After a further update here is the Fram volume export graph: more export than in 2017 less than the long time (2000-2017) average.

47
Arctic sea ice / Re: Latest PIOMAS update (October mid-monthly update)
« on: October 19, 2018, 02:54:22 PM »
Daily regional volume data is updated:
:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

The ice-velocity data was not updated, so the Fram volume export graph will have to wait.

48
Arctic sea ice / Re: Latest PIOMAS update (October mid-monthly update)
« on: October 19, 2018, 02:44:00 PM »
Daily volume and volume-anomaly graphs.

49
Arctic sea ice / Re: Latest PIOMAS update (October mid-monthly update)
« on: October 19, 2018, 02:25:27 PM »
The PIOMAS gridded thickness data has updated, last day 15 October.
Volume (calculated from thickness) at that day was 5.53 [1000 km3], third lowest behind 2012 and 2016 and just below 20122011 (5.55 [1000 km3])

Here is the animation for October.

50
Arctic sea ice / Re: 2018 sea ice area and extent data
« on: October 10, 2018, 05:52:57 PM »
The Basin-only NSIDC graphs are starting to look very strange, particularly the area graph.

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