Support the Arctic Sea Ice Forum and Blog

Author Topic: Home brew AMSR2 extent & area calculation  (Read 1974344 times)

seaicesailor

  • Guest
Re: Home brew AMSR2 extent & area calculation
« Reply #2450 on: July 29, 2016, 09:26:17 PM »

Regional delta map of Beaufort is attached. The big extent decline is in the eastern half.
Much of that appendix that is flash-melting was thick MYI; this gives an idea of the heat in the Beaufort sea. More old ice will be pushed further toward the coast in the next three days or so.

Gray-Wolf

  • Grease ice
  • Posts: 948
    • View Profile
  • Liked: 131
  • Likes Given: 458
Re: Home brew AMSR2 extent & area calculation
« Reply #2451 on: July 29, 2016, 11:38:32 PM »

It has the appearance of a very large area of ice that was approximately the same thickness at the start of the melt season (~1.85M or so?) reaching a critical point in its melt.

Presuming moderately consistent energy applied over time over the area, it would make sense for it to reach the same stage at about the same time.

I also have to wonder if the lack of 'deep cold' over winter gave this years ice a head start on 'softening' toward melt?

We know the pack has collapsed along fracture lines from past fracture events so we also have small floe size dominating in some areas leading to a quickening in melt overall compared to years with larger floe sizes?
KOYAANISQATSI

ko.yaa.nis.katsi (from the Hopi language), n. 1. crazy life. 2. life in turmoil. 3. life disintegrating. 4. life out of balance. 5. a state of life that calls for another way of living.
 
VIRESCIT VULNERE VIRTUS

peterlvmeng

  • Frazil ice
  • Posts: 143
    • View Profile
  • Liked: 35
  • Likes Given: 9
Re: Home brew AMSR2 extent & area calculation
« Reply #2452 on: July 30, 2016, 04:54:23 AM »
cliff is approaching

magnamentis

  • Guest
Re: Home brew AMSR2 extent & area calculation
« Reply #2453 on: July 30, 2016, 11:17:32 AM »
cliff is approaching

predicted since long and you're right of course. glad to see more people seeing things coming that 2-3 people were predicting back in late may early june :-) welcome to the club.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2454 on: July 30, 2016, 12:11:54 PM »
Update 20160729.

Extent: -61.9 (-191k vs 2015, -474k vs 2014, -323k vs 2013, +181k vs 2012)
Area: -123.0 (-225k vs 2015, -816k vs 2014, -586k vs 2013, -205k vs 2012)
 
You will find the updated graphs in the top post

Regional extent changed little, most in the Laptev: -21k.

Regional area plummeted in the CAB: -98k, elsewhere small changes only.

Attached is the delta map for the Laptev region. Lots of reds and blues inicate the ice is on the move. Also work on the "New Siberian Islands Bite" seems to be in progress.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2455 on: July 30, 2016, 12:19:12 PM »
For the ice in the Beaufort it is a bad place to be.

peterlvmeng

  • Frazil ice
  • Posts: 143
    • View Profile
  • Liked: 35
  • Likes Given: 9
Re: Home brew AMSR2 extent & area calculation
« Reply #2456 on: July 30, 2016, 12:33:40 PM »
cliff is approaching

predicted since long and you're right of course. glad to see more people seeing things coming that 2-3 people were predicting back in late may early june :-) welcome to the club.

Actually, it was in my middle school(2007), when I start to get aware of the severity of the vulnerable arctic sea ice. The winter seems cold in my experience after the record break extent(2007,2012) , because of lasting negative Arctic oscillation. You see people tend to regard the ENSO as an indicator to explain some extreme weather events, etc. Undoubtedly, the pacific ocean has the largest area and its surface temperature variation will inevitably influence the global atmosphere circulation. Let us return the sea ice in arctic. The sea ice doesn't seem to be an indicator as important as ENSO. But we have to admit that the arctic sea ice will be seasonal ice like the Antarctic in the near future. The huge different properties of underlying surface--ice and open sea that influence atmosphere is completely different. I am not sure which indicator will be more influential in the future. Also, the greenland ice sheet which govern the global sea level will be more vulnerable without the protection of sea ice in the summer. So, I wonder what new climate pattern will it brings about in the future.

Darvince

  • Frazil ice
  • Posts: 318
    • View Profile
  • Liked: 31
  • Likes Given: 7
Re: Home brew AMSR2 extent & area calculation
« Reply #2457 on: July 30, 2016, 01:04:21 PM »
With these huge area drops I might say that the cliff is here.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2458 on: July 31, 2016, 10:00:49 AM »
Update 20160730.

Extent: -68.1 (-152k vs 2015, -496k vs 2014, -379k vs 2013, +203k vs 2012)
Area: -88.9 (-201k vs 2015, -953k vs 2014, -560k vs 2013, -218k vs 2012)
 
You will find the updated graphs in the top post

The regions that changed most in extent were the CAB (-26k) and Laptev (-24k).

The CAB keeps dropping in area: -75k. CAA saw an uptick of +27k.

Concluding with an animation of a section including the Chukchi and ESS seas. Most of the (CAB region) area drop comes from here. The developing "bites" in the ice pack originating from both seas seem to start connecting.

werther

  • Grease ice
  • Posts: 747
    • View Profile
  • Liked: 31
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2459 on: July 31, 2016, 10:08:47 AM »
Thanks, Wipneus.
You picked the decisive battleground in your animation. I mean, this is about where extent might dive under 15% soon and produce a 500K drop.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2460 on: July 31, 2016, 10:29:55 AM »
And the ice surface melt extent derived from ADS/Jaxa AMSR2 data in the past week. Like extent/area, 2016 is closest to 2015 and 2012 and much further than 2013 and 2014.

magnamentis

  • Guest
Re: Home brew AMSR2 extent & area calculation
« Reply #2461 on: July 31, 2016, 11:21:02 AM »
Thanks, Wipneus.
You picked the decisive battleground in your animation. I mean, this is about where extent might dive under 15% soon and produce a 500K drop.

good man, you find the right words while i with my mediocre english skills always have to struggle to find the
right words. you're wording is impecable (as always)

thanks for adding to my learning curve :-)

seaicesailor

  • Guest
Re: Home brew AMSR2 extent & area calculation
« Reply #2462 on: July 31, 2016, 11:34:31 AM »
Thanks, Wipneus.
You picked the decisive battleground in your animation. I mean, this is about where extent might dive under 15% soon and produce a 500K drop.
And there is one more storm to pass by before it clears up and from the drift maps it is going to be as ugly.
Area-wise I'd dare to say that the aggregated effect of all these storms goes on par the GAC, only that was more final, and it is yet to be seen what happens with all this mess. But these last storms have been dragging a lot of heat ('ridged' some say).
I don't agree July had ice-protecting weather. Had a lot of yin-yang.

jdallen

  • Young ice
  • Posts: 3410
    • View Profile
  • Liked: 650
  • Likes Given: 244
Re: Home brew AMSR2 extent & area calculation
« Reply #2463 on: July 31, 2016, 09:49:01 PM »
Update 20160730.

Extent: -68.1 (-152k vs 2015, -496k vs 2014, -379k vs 2013, +203k vs 2012)
Area: -88.9 (-201k vs 2015, -953k vs 2014, -560k vs 2013, -218k vs 2012)
<snip>
The regions that changed most in extent were the CAB (-26k) and Laptev (-24k).

The CAB keeps dropping in area: -75k. CAA saw an uptick of +27k.

Concluding with an animation of a section including the Chukchi and ESS seas. Most of the (CAB region) area drop comes from here. <snip>
The areas in question ended the refreeze season with a lot of sub-2.5M ice. 
(Image reference below, link also on Neven's Arctic graphics page. www.cpom.ucl.ac.uk/csopr/seaice.html)
This ice has been melting at greater or lesser rates since around mid-May. With SST's now rising above -1.5C over wide swaths of the regions in question (2nd image), ice which has lost considerable thickness to surface melt and increasing bottom melt, is entering into the period of peak bottom melt.

Sea water temps even just as high as -1C will strip away more than 1CM/day of MYI, much less FYI.  By the time we reach the -0.5C range, we are looking at as much as 3CM/day of bottom melt.  If it gets much above that, things become worse quite rapidly; 0C temperatures will produce nearly 5CM/day of melt, which I think may happen locally very easily with open water and insolation.

If our ice is under 1M - which I believe much of it is - soon Werther's words may turn out to be prophetic:

Quote
Thanks, Wipneus.
You picked the decisive battleground in your animation. I mean, this is about where extent might dive under 15% soon and produce a 500K drop.
« Last Edit: July 31, 2016, 09:59:39 PM by jdallen »
This space for Rent.

AmbiValent

  • Frazil ice
  • Posts: 136
    • View Profile
  • Liked: 7
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2464 on: July 31, 2016, 10:06:58 PM »
I don't think there is a chance for ice to be below 1M this year. Maybe below 3M (unlikely, thankfully), but I now guess it's somewhere between 3,25M and 3,5M. (I had feared it would be a new record low earlier this year, though)

Oops, with 1M you clearly meant 1 meter thickness in this region, not 1 million square kilometers extent or area. Sorry.
Bright ice, how can you crack and fail? How can the ice that seemed so mighty suddenly seem so frail?

Rob Dekker

  • Nilas ice
  • Posts: 2386
    • View Profile
  • Liked: 120
  • Likes Given: 119
Re: Home brew AMSR2 extent & area calculation
« Reply #2465 on: August 01, 2016, 10:04:54 AM »
There is no shame in reporting the truth.
Bottom-melt is running the show right now, as shown by IMB 2015J at 77.80 N, 157.16 W.


This is our planet. This is our time.
Let's not waste either.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2466 on: August 01, 2016, 05:10:37 PM »
A solid extent drop and an area increase bring the 2016 numbers closer to those of 2015 and 2012.

Update 20160731.

Extent: -81.5 (-94k vs 2015, -522k vs 2014, -405k vs 2013, +145k vs 2012)
Area: +25.7 (-35k vs 2015, -930k vs 2014, -524k vs 2013, -105k vs 2012)
 
You will find the updated graphs in the top post

Regional extent drops in the ESS (-28k) and  Greenland Sea (-20k).

Regional area inceased in the CAB (+39k) and Chukchi (+21k). Laptev (-30k) and Greenland Sea (-19k) declined.

The regional delta map is from Chukchi and ESS regions (yesterday's animation).  As commented strong winds (from left to right in the image) and precipitation (most likely snow) are now the battered ice. The concentration increase here is no doubt temporary.


Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2467 on: August 01, 2016, 05:16:20 PM »
Animation of the Greenland Sea, no Fram export whatsoever, remaining ice is melting fast.

jdallen

  • Young ice
  • Posts: 3410
    • View Profile
  • Liked: 650
  • Likes Given: 244
Re: Home brew AMSR2 extent & area calculation
« Reply #2468 on: August 01, 2016, 05:38:30 PM »
There is no shame in reporting the truth.
Bottom-melt is running the show right now, as shown by IMB 2015J at 77.80 N, 157.16 W.


3-4CM a day. In line with my estimates.
This space for Rent.

seaicesailor

  • Guest
Re: Home brew AMSR2 extent & area calculation
« Reply #2469 on: August 01, 2016, 06:54:37 PM »
Animation of the Greenland Sea, no Fram export whatsoever, remaining ice is melting fast.

Yes. OTOH there is a steady ice transport toward Svalbard. A 15-20 km diameter floe can be seen North of the archipelago traveling about 80 km during the 10 days.
If this was happening along the huge Atlantic front, it'd be like 80x1,200 km = 100,000 km2. Take half of the Atlantic front, still 50,000 km2 in ten days.
This has been a constant this year with so many storms, difficult to put a number to this drift. The exported area would be in the hundreds of thousands (200k? 300k?)

To put this in perspective, turns out that the mean monthly Fram ice area export of the order of 80,000 km2, slower in summer. Let's say a very bad year has 100,000 km2 per month in summer.

https://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-4-12.html

AmbiValent

  • Frazil ice
  • Posts: 136
    • View Profile
  • Liked: 7
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2470 on: August 01, 2016, 07:15:22 PM »
Hmm... how to put it best? In the "old Arctic", Fram export was when ice was pushed through Fram Strait by Arctic currents. Sometimes there were stronger currents through the Fram, sometimes currents went into other directions, preventing the ice from leaving. And sometimes the ice could even get stuck when the whole width of Fram Strait was filled with ice.

In the "new Arctic", this "getting stuck" wouldn't happen anymore. The currents that sometimes go right through the Fram and sometimes into other directions are still there. That should improve Fram export.

But there's yet another new development working against it, which is warmer Atlantic currents meeting the ice front when it is still north of the Fram, melting ice right there. That ice would most likely have gone through the Fram and melt south of it, but now it won't be counted into export since it never passed Fram Strait.

Maybe we need a more complicated metric than the simple one we had used in the past to catch the new developments along the Atlantic-Arctic ice front...
Bright ice, how can you crack and fail? How can the ice that seemed so mighty suddenly seem so frail?

A-Team

  • Young ice
  • Posts: 2977
    • View Profile
  • Liked: 944
  • Likes Given: 35
Re: Home brew AMSR2 extent & area calculation
« Reply #2471 on: August 01, 2016, 07:59:30 PM »
Just for everyone's future convenience in relating Modis visible at the WorldView portal to AMSR2 3.1215k large format sea ice concentration map at the UH archive, I verified that they can be rescaled to align near perfectly, as expected since both use the same NSIDC standard polar stereographic projection EPSG 3413 (70º + central meridian -45º aka Greenland down).

The Modis frame of 31 July 16 was captured with the WorldView snapshot feature set to 5 km/pixel scale (presumably meaning at 70º N) rather than an unspecified zoom level. This is a good scale for the entire Arctic Ocean staying within forum bounds of 700x700 pixels.

To rescale, the AMSR2 must be reduced by 38.045%, which of course will ruin the sea ice concentration palette. That's for the large format so 76.09% will do for the small format png.

Alternatively the 5 km WorldView can be enlarged by 262.85% which will change its scale from 5 to 1.9023 km/pxl (respectively 131.42% and 3.8045 km/pxl to fit the small AMRS2 format). These retain the 100 color palette. (It's easy to get scale factors inverted so this post may be edited in the near future.)

The intermediate frames show various ways (gimp modes) of combining AMSR and Worldview into a single concentration vs surface/clouds image.
« Last Edit: August 02, 2016, 03:35:26 AM by A-Team »

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2472 on: August 02, 2016, 09:13:34 AM »
First of the month: I estimate no more than -10k extent is lost because the monthly ocean mask has changed.

Update 20160801.

Extent: -91.5 (-97k vs 2015, -568k vs 2014, -450k vs 2013, +42k vs 2012)
Area: -128.2 (-97k vs 2015, -950k vs 2014, -602k vs 2013, -141k vs 2012)
 
You will find the updated graphs in the top post

Regional extent declines are moderate. Only Laptev and Beaufort (both -17k) deserve mentioning.

Area in the ESS dropped most: -55k. More declines in Laptev (-20k), CAA (-18k) and CAB (-16k).

Same delta map as yesterday. The cyclone moved position which is reflected in changes in concentration and size of the polynya. Those in the New Siberian Island Bite seem to grow.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2473 on: August 02, 2016, 09:18:08 AM »
Animation of the Canadian Archipelago sea ice concentration. The northern branches of the NW passage are weakening as well.

 

seaicesailor

  • Guest
Re: Home brew AMSR2 extent & area calculation
« Reply #2474 on: August 02, 2016, 09:22:32 AM »
The breach that I suspect caused by underlying current at Chukchi sea has been blurred and displaced. It will be interesting to see if it reappears or is reinforced at the same location as before.
Thank you Wipneus for your amazing work.

Juan C. García

  • Young ice
  • Posts: 3359
    • View Profile
  • Liked: 1279
  • Likes Given: 1127
Re: Home brew AMSR2 extent & area calculation
« Reply #2475 on: August 03, 2016, 01:42:45 AM »
First of the month: I estimate no more than -10k extent is lost because the monthly ocean mask has changed.

Pardon my ignorance, but what is "the monthly ocean mask"? Maybe will be better to include the meaning in the Glossary.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Feeltheburn

  • Frazil ice
  • Posts: 214
    • View Profile
  • Liked: 12
  • Likes Given: 8
Re: Home brew AMSR2 extent & area calculation
« Reply #2476 on: August 03, 2016, 08:09:39 AM »
Animation of the Canadian Archipelago sea ice concentration. The northern branches of the NW passage are weakening as well.

Is the Northwest Passage completely open now?  Has this been reported?  thanks in advance.
Feel The Burn!

Rob Dekker

  • Nilas ice
  • Posts: 2386
    • View Profile
  • Liked: 120
  • Likes Given: 119
Re: Home brew AMSR2 extent & area calculation
« Reply #2477 on: August 03, 2016, 09:50:31 AM »
Is the Northwest Passage completely open now?  Has this been reported?  thanks in advance.

This thread :
http://forum.arctic-sea-ice.net/index.php/topic,762.200.html
deals with that question in detail.
This is our planet. This is our time.
Let's not waste either.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2478 on: August 03, 2016, 03:41:48 PM »
First of the month: I estimate no more than -10k extent is lost because the monthly ocean mask has changed.

Pardon my ignorance, but what is "the monthly ocean mask"? Maybe will be better to include the meaning in the Glossary.

These masks, created by NSIDC, remove any ice from places where we know no ice does exist. As ice in winter can be found much further south than in summer, a different mask has been created for each month.

They are created by NSIDC for their sea ice concentration product, but I know that Uni Hamburg and OSI/SAF also use them, after adapting for different resolution of course.

http://nsidc.org/data/smmr_ssmi_ancillary/ocean_masks.html

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2479 on: August 03, 2016, 04:01:32 PM »
Big declines, 2016 stays close with 2012 and 2015, but 2013 and 2104 stay behind.

Update 20160802.

Extent: -131.6 (-125k vs 2015, -627k vs 2014, -501k vs 2013, +15k vs 2012)
Area: -135.6 (-103k vs 2015, -964k vs 2014, -710k vs 2013, -177k vs 2012)
 
You will find the updated graphs in the top post

Extent in the Laptev dropped most: -32k. Beaufort (-22k), CAB (-17k) and ESS (-14) follow.

Area was dropped most by the CAB (-49k), followed by ESS (-27k), Beaufort (-19k) and Chukchi (-16k).

Attached is a side by side animation of the Arctic Basin in 2016 and 2015. Low concentration ice penetrates much further towards the pole. How much will that account in the final part of the race?

Must click to start.

Darvince

  • Frazil ice
  • Posts: 318
    • View Profile
  • Liked: 31
  • Likes Given: 7
Re: Home brew AMSR2 extent & area calculation
« Reply #2480 on: August 03, 2016, 04:12:54 PM »
Big declines, 2016 stays close with 2012 and 2015, but 2013 and 2104 stay behind.
Erm, wouldn't 2104 be way, way ahead by this date?  ;D

effbeh

  • New ice
  • Posts: 19
    • View Profile
  • Liked: 0
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2481 on: August 03, 2016, 04:40:51 PM »
Attached is a side by side animation of the Arctic Basin in 2016 and 2015. Low concentration ice penetrates much further towards the pole. How much will that account in the final part of the race?

This going to be quite interesting.  As clouds allow us to sneak a peek, an astonishing amount of ice
doesn't look too good.  Definitely much worse than the 2015 comparison.  And there's still plenty of
time to go before the melt season is over.

Feeltheburn

  • Frazil ice
  • Posts: 214
    • View Profile
  • Liked: 12
  • Likes Given: 8
Re: Home brew AMSR2 extent & area calculation
« Reply #2482 on: August 04, 2016, 02:44:21 AM »
Is the Northwest Passage completely open now?  Has this been reported?  thanks in advance.

This thread :
http://forum.arctic-sea-ice.net/index.php/topic,762.200.html
deals with that question in detail.

Thanks!
Feel The Burn!

Juan C. García

  • Young ice
  • Posts: 3359
    • View Profile
  • Liked: 1279
  • Likes Given: 1127
Re: Home brew AMSR2 extent & area calculation
« Reply #2483 on: August 04, 2016, 03:37:39 AM »
First of the month: I estimate no more than -10k extent is lost because the monthly ocean mask has changed.

Pardon my ignorance, but what is "the monthly ocean mask"? Maybe will be better to include the meaning in the Glossary.

These masks, created by NSIDC, remove any ice from places where we know no ice does exist. As ice in winter can be found much further south than in summer, a different mask has been created for each month.

They are created by NSIDC for their sea ice concentration product, but I know that Uni Hamburg and OSI/SAF also use them, after adapting for different resolution of course.

http://nsidc.org/data/smmr_ssmi_ancillary/ocean_masks.html

Thanks Wipneus! And thanks for all this work!  ;)
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2484 on: August 04, 2016, 07:55:26 AM »
I may not have time for making a detailed report and/or images today. For now just the summary:

Update 20160803.

Extent: -149.0 (-138k vs 2015, -686k vs 2014, -581k vs 2013, +69k vs 2012)
Area: -118.0 (-185k vs 2015, -998k vs 2014, -788k vs 2013, -240k vs 2012)
 
You will find the updated graphs in the top post

(extent losses in CAA (-37k), Laptev (-28k) and ESS (-27k)

FishOutofWater

  • Nilas ice
  • Posts: 1088
    • View Profile
  • Liked: 696
  • Likes Given: 332
Re: Home brew AMSR2 extent & area calculation
« Reply #2485 on: August 04, 2016, 05:49:42 PM »
Another huge drop in both extent and area and based on today's big compaction in the ESS and growth of the Laptev bite it looks like another big drop tomorrow.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2486 on: August 04, 2016, 06:38:34 PM »
Animation of Beaufort sea ice concentration. Looking at the regional area graph area is approaching zero as the last ice floes disintegrate.


Steven

  • Grease ice
  • Posts: 957
    • View Profile
    • Arctic sea ice data and graphs
  • Liked: 481
  • Likes Given: 19
Re: Home brew AMSR2 extent & area calculation
« Reply #2487 on: August 04, 2016, 08:52:52 PM »
Update 20160803.

Extent: -149.0 (-138k vs 2015, -686k vs 2014, -581k vs 2013, +69k vs 2012)
Area: -118.0 (-185k vs 2015, -998k vs 2014, -788k vs 2013, -240k vs 2012)

Wipneus,  according to those numbers, the sea ice area in 2015 was 55 thousand km2 below 2012 at this date.  As discussed earlier in this thread, your numbers for 2012 are calculated from UH SSMIS data whereas the numbers for 2013-2016 are from UH AMSR2 data.  The graphs you posted a few weeks ago (in Reply #2384) suggest that this could affect the calculation of sea ice area by about 0.3 million km2 or so at this time of year (look at the data for August/September 2013 in that graph).  So this could affect the ranking of 2012 vs. the other years in your daily reports?


Moreover, looking at the compactness graph in the top post of this thread:
 


the calculations with Uni Hamburg data in this graph (blue and black curves) suggest that compactness in 2012 was substantially higher than in 2015 and 2016 at this time of year.  Whereas the calculations with JAXA data (green curves) suggest the opposite: compactness in 2012 was lower than in 2015 and 2016 at this time of year.  Which is more realistic?

Rob Dekker

  • Nilas ice
  • Posts: 2386
    • View Profile
  • Liked: 120
  • Likes Given: 119
Re: Home brew AMSR2 extent & area calculation
« Reply #2488 on: August 05, 2016, 07:50:22 AM »
Steven,
I'm going to let Wipneus comment on the details, but I don't see much of any evidence of a bias between Wipneus' UH SSMIS 2012 and AMSR data. And certainly not a 300 k bias.

For example, in Wipneus comparative graphs in the reference you gave
http://forum.arctic-sea-ice.net/index.php/topic,382.msg84161.html#msg84161
during the 2014 melting season there is virtually no difference to speak of.

What makes you think there is a 300 k difference now in (August) 2016, or in August 2015 ?
This is our planet. This is our time.
Let's not waste either.

Rob Dekker

  • Nilas ice
  • Posts: 2386
    • View Profile
  • Liked: 120
  • Likes Given: 119
Re: Home brew AMSR2 extent & area calculation
« Reply #2489 on: August 05, 2016, 08:07:42 AM »
Regarding the concentration index differences, again, I'll leave the details to Wipneus, but this difference appears to have more to do with the choice of algorithm (ASI/bootstrap/NASA team) than with the resolution of the source.
This is our planet. This is our time.
Let's not waste either.

Steven

  • Grease ice
  • Posts: 957
    • View Profile
    • Arctic sea ice data and graphs
  • Liked: 481
  • Likes Given: 19
Re: Home brew AMSR2 extent & area calculation
« Reply #2490 on: August 05, 2016, 02:23:35 PM »
I'm going to let Wipneus comment on the details, but I don't see much of any evidence of a bias between Wipneus' UH SSMIS 2012 and AMSR data. And certainly not a 300 k bias.

For example, in Wipneus comparative graphs in the reference you gave
http://forum.arctic-sea-ice.net/index.php/topic,382.msg84161.html#msg84161
during the 2014 melting season there is virtually no difference to speak of.

As shown in that graph, there was a persistent difference of about 200 to 300k between the 2 calculations of sea ice area at this time of year in 2013.  There was indeed better agreement between them in the 2014 melt season.  Unfortunately, 2014 and 2013 are the only 2 years for which the comparison in that graph is available.  So it's unclear what this means for the comparison of the UH SSMIS data for 2012 with the (unfortunately unavailable) UH AMSR2 2012 data.


Regarding the concentration index differences, again, I'll leave the details to Wipneus, but this difference appears to have more to do with the choice of algorithm (ASI/bootstrap/NASA team) than with the resolution of the source.

Sure.  But my question was which set of curves in the compactness graph should be preferred: the blue (+black) set of curves for 2012-2016, or the green set of curves for 2012-2016?  The comparison of 2012 vs. 2015/2016 is very different for them.
« Last Edit: August 05, 2016, 02:55:59 PM by Steven »

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2491 on: August 05, 2016, 04:23:34 PM »
Update 20160803.

Extent: -149.0 (-138k vs 2015, -686k vs 2014, -581k vs 2013, +69k vs 2012)
Area: -118.0 (-185k vs 2015, -998k vs 2014, -788k vs 2013, -240k vs 2012)

Wipneus,  according to those numbers, the sea ice area in 2015 was 55 thousand km2 below 2012 at this date.  As discussed earlier in this thread, your numbers for 2012 are calculated from UH SSMIS data whereas the numbers for 2013-2016 are from UH AMSR2 data.  The graphs you posted a few weeks ago (in Reply #2384) suggest that this could affect the calculation of sea ice area by about 0.3 million km2 or so at this time of year (look at the data for August/September 2013 in that graph).  So this could affect the ranking of 2012 vs. the other years in your daily reports?
It is more like 230k, which is really not bad for two different area calculations. But yes those are the margins of error that are inherent in this game.

You could add 230k to the difference numbers of 2012, and make an argument that that would be  a fairer game. I hesitate to do that, 2012  may not be like 2013 or 2014, and just adding an arbitrary number without much understanding is not much to my liking.

Quote



Moreover, looking at the compactness graph in the top post of this thread:
 
https://sites.google.com/site/arctischepinguin/home/amsr2/grf/amsr2-compact-compare.png

the calculations with Uni Hamburg data in this graph (blue and black curves) suggest that compactness in 2012 was substantially higher than in 2015 and 2016 at this time of year.  Whereas the calculations with JAXA data (green curves) suggest the opposite: compactness in 2012 was lower than in 2015 and 2016 at this time of year.  Which is more realistic?

I do not really have an answer, but:
About using the SSMIS data, since both extent and area of that calculation have similar and same sign offsets, you could expect compactness (the ratio of area and extent) to be quite close and not likely to cause this interesting observation.
In the second place looking at this graph you should realize that there are bigger differences between the data sets (NSIDC, Jaxa and Uni Hamburg), than between different years. You can make a point that the three compactness groups are different any way.
Another thought is that this graph is probably too simplified by taking the whole arctic number. In summer many regions that have nearly melted out, the ice there is, has a high proportion of marginal ice. There is a rather ugly regional compactness graph, that makes the chaotic behavior of such marginal ice compactness clear. Unfortunately I had to leave Jaxa out to keep that graph readable. 

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2492 on: August 05, 2016, 05:12:47 PM »
Update 20160804.

Extent: -52.0 (-173k vs 2015, -670k vs 2014, -592k vs 2013, +113k vs 2012)
Area: +11.0 (-98k vs 2015, -868k vs 2014, -719k vs 2013, -81k vs 2012)
 
You will find the updated graphs in the top post

Regional extent changes are small, except ESS that dropped -26k.

CAB area increased by +43k, Laptev dropped -21k.

Attached is the delta map of the Arctic Basin. The ice edge is retreating along a long stretch in the ESS (and beyond). Expanding along the Atlantic ice edge. All quite well explained by the wind directions.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2493 on: August 05, 2016, 05:17:26 PM »
An animation of Barents section. The expanding ice edge mentioned above can be observed well here.

(needs a click)

Shared Humanity

  • Guest
Re: Home brew AMSR2 extent & area calculation
« Reply #2494 on: August 05, 2016, 10:17:35 PM »
Ice melts pretty quickly as it moves towards the Barents.

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2495 on: August 06, 2016, 12:25:15 PM »
Update 20160805.

Extent: -128.6 (-323k vs 2015, -773k vs 2014, -678k vs 2013, +231k vs 2012)
Area: -72.4 (-81k vs 2015, -905k vs 2014, -717k vs 2013, -9k vs 2012)
 
You will find the updated graphs in the top post

Regional extent dropped again big in the same corner: CAB (-47k), ESS (-35k) and Chukchi (-25k).

Regional area declines are more moderate, Chukchi (-18k), Laptev (-17k), CAB (-15k) and CAA (-15k).

Attached a delta map of Beaufort and Chukchi section illustration the extent losses in Chukchi and CAB. It is especially eating in the Chukchi bite. The bluish ice to the right indication sea ice concentration increases coincidences with a snow fall seen in the nullschool site.


Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2496 on: August 06, 2016, 12:36:35 PM »
Animation of the Canadian Archipelago. Some of the ice in the Viscount Melville St. is blown to the south, leaving a clear stretch on the northern side.

JayW

  • Grease ice
  • Posts: 607
    • View Profile
  • Liked: 226
  • Likes Given: 292
Re: Home brew AMSR2 extent & area calculation
« Reply #2497 on: August 06, 2016, 01:05:05 PM »

The bluish ice to the right indication sea ice concentration increases coincidences with a snow fall seen in the nullschool site.

Can't express my gratitude enough for all the work you do Wipneus.  Many thanks.

I know I'll catch flak for this, and certainly not trying to be adversarial, but I honestly can't fathom that that could be snow.  According to the ECMWF, there was quite a plume of warm air at 850mb, that would not support snow. As seen in attachment 1.

http://www.tropicaltidbits.com/analysis/models/?model=ecmwf&region=ak&pkg=T850&runtime=2016080512&fh=0&xpos=0&ypos=164

Second attachment is an animation of yesterday from about 12z-23z, showing a persistent band of clouds over that area.  Could the clouds cause this effect? 

http://feeder.gina.alaska.edu/search?utf8=✓&search%5Bsensors%5D%5B3%5D=1&search%5Bfeeds%5D%5B16%5D=1&search%5Bfeeds%5D%5B1%5D=1&search%5Bfeeds%5D%5B15%5D=1&search%5Bfeeds%5D%5B17%5D=1&search%5Bfeeds%5D%5B3%5D=1&search%5Bfeeds%5D%5B18%5D=1&search%5Bfeeds%5D%5B10%5D=1&search%5Bfeeds%5D%5B11%5D=1&search%5Bfeeds%5D%5B9%5D=1&search%5Bfeeds%5D%5B8%5D=1&search%5Bfeeds%5D%5B12%5D=1&search%5Bfeeds%5D%5B13%5D=1&search%5Bfeeds%5D%5B14%5D=1&search%5Bfeeds%5D%5B6%5D=1&search%5Bfeeds%5D%5B5%5D=1&search%5Bstart%5D=&search%5Bend%5D=&commit=Search

I know my satellite interpretation skills are questionable.  But I've tracked many winter storms, and understand quite well, the dendritic growth zone (where snowflakes are made in the atmosphere).  And that moisture plume would be a rain cloud in my uneducated opinion.   :) 

Just trying to understand it all better.  Thanks again.

"To defy the laws of tradition, is a crusade only of the brave" - Les Claypool

seaicesailor

  • Guest
Re: Home brew AMSR2 extent & area calculation
« Reply #2498 on: August 06, 2016, 01:37:03 PM »
What about compaction?

Wipneus

  • Citizen scientist
  • Young ice
  • Posts: 4220
    • View Profile
    • Arctische Pinguin
  • Liked: 1025
  • Likes Given: 0
Re: Home brew AMSR2 extent & area calculation
« Reply #2499 on: August 06, 2016, 01:43:50 PM »

The bluish ice to the right indication sea ice concentration increases coincidences with a snow fall seen in the nullschool site.

Can't express my gratitude enough for all the work you do Wipneus.  Many thanks.

I know I'll catch flak for this, and certainly not trying to be adversarial, but I honestly can't fathom that that could be snow.  According to the ECMWF, there was quite a plume of warm air at 850mb, that would not support snow. As seen in attachment 1.


Do not trust me on the weather. Nullschool indicates surface temperatures there are a bit below zero (-0.4 oC or so), combined with my expectation and some experience that rain would give lower apparent sea ice concentration makes me say snow.  There is the influence of that band of clouds as well of course.