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Messages - Wipneus

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1
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 21, 2019, 02:12:00 PM »
NSIDC NT sea ice extent and area in the Arctic Basin (where most of the last summer ice will be) continue to drop fast.

2
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 09, 2019, 06:57:03 PM »
NSIDC NT sea ice extent and area in the Arctic Basin (you know what I mean) are now both below anything previously on the 8th of May.

3
Antarctica / Re: PIG has calved
« on: May 05, 2019, 04:59:33 PM »
Six days have passed and a Sentinel is again in the same orbital position.

Update of my last animation with another frame.

Click to make it start.

4
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 05, 2019, 02:03:09 PM »
NSIDC NT sea ice extent and area in the Basin (Beaufort, Chukchi, ESS, Laptev and Cental Basin) continue to drop fast. Area is below anything before in the first days of May.

5
Arctic sea ice / Re: Latest PIOMAS update (May 2019)
« on: May 04, 2019, 02:39:12 PM »
Thickness map for 30th of April 2019, compared with previous years and the differences.

7
Arctic sea ice / Re: Latest PIOMAS update (May 2019)
« on: May 04, 2019, 10:01:43 AM »
Fram export (volume) was on average low in April.

8
Arctic sea ice / Re: Latest PIOMAS update (May 2019)
« on: May 04, 2019, 09:58:27 AM »
Here are the volume and volume-anomaly graphs. The 2019 volume  is very close with 2011, 2016 and 2018. Virtually sharing second (lowest) place.

9
Arctic sea ice / Re: Latest PIOMAS update (May 2019)
« on: May 04, 2019, 08:34:52 AM »
PIOMAS gridded thickness data has updated. AFAICS the official volume data net yet.
Volume on 30th April was 22.34 [1000 km3]. This is the fourth lowest but the differences with third and fifth place are so small that the official volume data may disagree.

Here is the animation for April.

10
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 01, 2019, 02:38:58 PM »
NSIDC NT extent and area for the Basin only. Extent is just starting to drop from 100%  ice, while sea ice area has now dropped to low records for the day.

11
Antarctica / Re: PIG has calved
« on: May 01, 2019, 09:03:15 AM »
@Wipneus Is that Sentinel-1 or 2?  Also, what is your secret to getting such gorgeous images from SAR?  I assume your tool chain is SNAP and Gimp, but I'm struggling getting anything comparable.

Hi baking,

It is Sentinel 1 of course (corrected the text). Thanks!

I am downloading the data from the Copernicus Open Access Hub (scihub.copernicus.eu). In particular I am using the access script dhusget supplied by ESA (https://scihub.copernicus.eu/twiki/do/view/SciHubUserGuide/BatchScripting?redirectedfrom=SciHubUserGuide.8BatchScripting).

Unpacking in a bash script, rotation and adjusting the contrast with ImageMagick.

Last step is indeed with The Gimp: combining, aligning, cropping, scaling and adding texts.

So the only thing I do that has any influence on the image quality ( apart from selecting the most suitable images rom scihub) is the "-contrast-stretch 0x0.025%"  option in ImageMagick.

12
Antarctica / Re: PIG has calved
« on: April 29, 2019, 08:12:07 PM »
Six days later, and now the development can be even seen on this short time interval. Things are speeding up.

Higher resolution -> need a click to start the animation.

EDIT: subscript showed "Sentinel 2", it is "Sentinel 1" of course

13
Antarctica / Re: PIG has calved
« on: April 25, 2019, 10:55:18 AM »
Estimating speed at the calving front. The shift between the two images in native resolution (10m/pix) is 47 pixels down and 4 to the left. With 36 days in between that works out to

13.1 [m/day]

With an measurement error of about 2 pix => +/- 0.5 [m/day]). When I started doing these estimates (in 2014, see this thread), speed was "only" 9-10 [m/day].

14
Antarctica / Re: PIG has calved
« on: April 25, 2019, 10:40:52 AM »
Both cracks developing as seen in these two Sentinel 1 images, taken 36 days apart.

15
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: April 22, 2019, 03:42:48 PM »
Large area drop in Greenland Sea Region today:

torching in Fram Strait and above.

17
Wouldn't 20.74 put it below 2018?

Indeed, I took it from the wrong (sorted) table, 20.74 is for 2017 (lowest value). The corrected value (22.46) is in the post now.

18
The daily volume and volume-anomaly graphs.

19
Fram volume export appears to have been very low in the first half of the month.

20
PIOMAS has updated the gridded thickness data up the 15th of April. My calculated volume for that day is 20.74 22.46 [1000km3]. This is third lowest day-value behind 2017 and 2018.

Here is the animation for April sofar.

FIXED: correct volume

21
Antarctica / Re: PIG has calved
« on: April 17, 2019, 11:47:44 AM »

In my opinion the SW crack (the low left one in Sentinel, the right one in Wipneus' post) has grown, widened and lengthened since then.

PS. these Sentinel Images are from identical orbital positions.


Mostly yes. Here is an animation of a month of Sentinel 1 A/B images showing changes in the other crack as well, less pronounced perhaps.

As a result from the 10m/pix resolution, you must click the image for the better view.

22
Antarctica / Re: PIG has calved
« on: April 14, 2019, 06:36:31 PM »
Very late in the season for an optical image but here it is. With a solar elevation of just 1.45 degrees (IIRC that is just three solar disks), the shadowed cracks are shown in exquisite detail.

Notice that the pair of major cracks are getting accompanied by a couple more to the right. This is a new feature, these new ones are not visible on a similar image 9 days older.

Uploaded in the native 15m/pix resolution, you must click the image for the better view.

24
Arctic sea ice / Re: Latest PIOMAS update (April 2019)
« on: April 03, 2019, 10:26:57 AM »
Fram volume(!) export was about normal for the month of March. The normals are indicated by the grey line in the background and are harder to see when exports are higher.

25
Arctic sea ice / Re: Latest PIOMAS update (April 2019)
« on: April 03, 2019, 09:58:01 AM »
Here is the thickness of 31st March, with comparisons with previous years and their differences.

26
Arctic sea ice / Re: Latest PIOMAS update (April 2019)
« on: April 03, 2019, 09:54:56 AM »
Thanks, Wip. As for the volume graph, I find it hard to discern the 2019 trend line, because of the 2016 trend line (colours are too similar). But could be my eyes or monitor.

Ack. That needs a fix.

28
Arctic sea ice / Re: Latest PIOMAS update (April 2019)
« on: April 03, 2019, 08:47:09 AM »
Volume and volume-anomaly graphs.

29
Arctic sea ice / Re: Latest PIOMAS update (April 2019)
« on: April 03, 2019, 08:46:07 AM »
PIOMAS  has updated, both the volume as the gridded thickness data.
Volume on 2019-03-31 was 22.218 [1000km3], fourth lowest for the day.

Here is the animation for March 2019.

30
Arctic sea ice / Re: Latest PIOMAS update (March)
« on: March 26, 2019, 11:56:22 AM »
The Fram export graph shows near normal export figures in Jan and Feb.
Is it possible for you to verify whether Fram export is thinner than previous years according to piomas?

Hi Uniquorn,

I have given this some thought and I'm wondering what it is you really want.

If volume export is less that can be because (not exclusive):

1. Ice thickness is less;
2. Ice thickness unchanged but concentration less.

Would calculating ice area export ( km2/month) answer your question?

31
Arctic sea ice / Re: Latest PIOMAS update (March mid-monthly update)
« on: March 19, 2019, 12:02:38 PM »
The regional daily volume data updated:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

No gridded ice velocity data updated, so no new Fram export data  :'(

32
Arctic sea ice / Re: Latest PIOMAS update (March mid-monthly update)
« on: March 19, 2019, 11:42:32 AM »
Volume and volume-anomaly graphs.

33
Arctic sea ice / Re: Latest PIOMAS update (March mid-monthly update)
« on: March 19, 2019, 11:37:50 AM »
PIOMAS has updated gridded thickness data. Volume calculated from this was 21.95 [1000km3] on the 15th of March. That would be the 7th lowest for the day.

Here is the animation of March until sofar.

35
Arctic sea ice / Re: Latest PIOMAS update (March)
« on: March 05, 2019, 06:50:14 PM »
The Fram export graph shows near normal export figures in Jan and Feb.

36
Arctic sea ice / Re: Latest PIOMAS update (March)
« on: March 05, 2019, 06:25:12 PM »
Thickness maps, compared with previous years and differences with those.

37
Arctic sea ice / Re: Latest PIOMAS update (March)
« on: March 05, 2019, 06:04:49 PM »
Since there was none last month, hre is the animation of Jan-Feb 2019.

38
Arctic sea ice / Re: Latest PIOMAS update (March)
« on: March 05, 2019, 12:52:46 PM »
Unfortunately the ftp server with the detailed thickness data has not been serving me for some time now. I will look into that..

That's a crying shame :(

Do you have any idea what the problem might be as yet?

Yes, they have moved to https :

old  ->  new
ftp://pscftp.apl.washington.edu/zhang/PIOMAS/data   ->
https://pscfiles.apl.uw.edu/zhang/PIOMAS/data


ftp is of course designed for automated computer data transfer, while https was designed for interactive browsing (with some incidentally downloading).

Looking at the required (wget) trickery to have the same level of automatisation as before.

39
Arctic sea ice / Re: Latest PIOMAS update (March)
« on: March 05, 2019, 08:49:10 AM »
PIOMAS has updated the official volume data. Unfortunately the ftp server with the detailed thickness data has not been serving me for some time now. I will look into that.

Here are the volume and volume-anomaly graphs.

40
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...

41
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.

42
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




43
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...


44
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

45
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:

46
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

47
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.

48
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.


49
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.

50
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.

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