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Tor Bejnar

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Re: The 2016 melting season
« Reply #3400 on: July 17, 2016, 01:15:01 AM »
A-Team,
Then what did JayW post (above) in Reply #3379  Today at 03:19:17 AM?
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JayW

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Re: The 2016 melting season
« Reply #3401 on: July 17, 2016, 01:25:10 AM »
I still say it's broken, I don't know the time stamp on A-Team's image, but this one is at July 16 1222z.

Edit: , added a second wider shot for reference

http://feeder.gina.alaska.edu/search?utf8=✓&search%5Bsensors%5D%5B4%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
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slow wing

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Re: The 2016 melting season
« Reply #3402 on: July 17, 2016, 02:30:57 AM »
Yep, RIP Big Block. It has just broken up.

In views from 3 different satellites from WorldView for 2016-07-16, Suomi and Terra see it intact but Aqua shows it broken up, even though partly obscured by cloud...

A-Team

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Re: The 2016 melting season
« Reply #3403 on: July 17, 2016, 07:04:50 AM »
Quote
then what did they post (above) ?
To be taken seriously, cloudy images with no coastal context or scale need the lat/lon of the feature under discussion and/or the WorldView url included in the post. If not WV, then it absolutely requires sourcing reproducible by others.

The former amounts to mousing over the feature and taking a screenshot of the lower right hand corner and pasting in a corner of the image they are posting.

The latter involves a copy/paste of the tinyurl supplied already by Nasa in the upper right corner (which allows others to reproduce the scene, find the scale, zoom in or out, and look at supplementary layers.

I cannot fathom how these two tasks together could add more than ten seconds to post preparation. It's the difference between making a claim and making a case.

A year from now, we'll be looking back at this forum a year as an important resource for the 2017 season, wishing we knew which posts had good insights and which were flat-out crazy. It is the documentation within the post that makes that decidable.

Post #3402 of slow wing is more interesting because it follows best practice of clicking through the three visible layers on WorldView with capture (#3399 also clicked through but saved only the clear one). These three visible layers are taken at slightly different times which is routinely helpful on getting past cloud cover.

The post goes on to discuss the vexatious issue of timestamps (rather lack thereof) and how this likely resolves interpretive conflicts. For a balanced post, both supporting and conflicting data need to be reconciled.

All three images change multiple times during the day before they are finalized and assigned a calendar date in the archives. The earliest versions are missing wedges and are not color-corrected for atmospheric scattering. Later versions have full Arctic Ocean coverage but are still temporary. These are not retained -- if you come back later, the earlier complete images are gone.

Somewhere, sometime during the 17 years these satellites have been in service, somebody surely documented the archival image building process (algorithm) in detail. Today it's just another black box pipeline on autopilot with most users not that concerned with real time events and satisfied with a single official archived version for the day. (There may be genuine issues with data volume necessitating this.)

JayW is making very good use of another site serving transient per-orbit imagery restricted to coastal and off-shore Alaska. This allows, in the case of peri-coastal floes splitting, rather narrow bounds on timing events because this data does have precise timestamps.

However the moment of floe fracturing may be of lessor importance for the Beaufort Gyre than this site's ability to display passing clouds and weather much better than sources like nullschool etc. which provide no explanation whatsoever this season for continued rotation in the absence of supporting surface winds.

There are questions though with this site's areal coverage and retention. They may have set up their own local ground station to receive a portion of satellite data directly. (Anyone can do this at home, the data is not encrypted, but multiple stations are needed to get a whole orbit's worth.) 

A good test case would be retrieving individual orbital passes over the historic Jakobshavn calving sequence of 15 Aug 15. My guess is that data is gone (or rather irrevocably assimilated into that day's product). Satellite date is just too voluminous to store everything, so it went into buffer for a time but has been over-written by now. Sentinel 2AB and Landsat-8 don't seem to even acquire the imagery in the first place for the CAB though S1A does.

We've discussed on another forum how some imagery now comes with a second low-bit grayscale layer that encodes the timestamp and source of each pixel. That's admirable but it adds to file size and complexity without seeing that much use.
« Last Edit: July 17, 2016, 07:31:33 AM by A-Team »

Rob Dekker

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Re: The 2016 melting season
« Reply #3404 on: July 17, 2016, 09:04:27 AM »
Regarding capture times, playing with WorldView's orbit mask, I found that between Aqua, Terra and Suomi, July 16 had 6 pictures taken of Big Block :

UTC 
6:55 Terra Ascending
14:05 Aqua Descending
14:05 Suomi Descending
20:30 Aqua Ascending
20:45 Suomi Ascending
21:50 Terra Descending

Now, in WorldView we can only see three of these pictures (one for each of the three satellites) :

20:30 Aqua :  Shows Big Block broken

20:45 Suomi : Shows Big Block broken

21:50 Terra : Shows Big Block in the clouds

Suggesting the breakup happened before 20:30 UTC.

With WorldView, I cannot reproduce the earlier Terra/Aqua/Suomi images that Jay and Slow Wing showed, but I'm sure that is because WorldView appears to present only the last picture of the day from each of the satellites.

Slow Wing's picture of an intact Big Block from Suomi, suggests that the breakup happened after 14:05 UTC (that is when Suomi made its descending run).

So there you have it. Big Block broke between 14:05 and 20:30 UTC on July 16.

Either way, it is clear that Big Block broke up in three pieces, which I'd like to call "Baby Block", "Kid Block" and "Mother Block" for lack of creativity :).

It is not immediately clear why it broke. No adjacent MYI block appears to have collided. So maybe just shear exhaustion (bottom melt) and the winds of that cyclone did the job ?

[edit] One could argue that Big Block broke up in 4 pieces, not 3.
That is an opportunity for better naming of Big Block's offspring.
And note that Mother Block is still a VERY large chuck of ice, which will survive at least a couple of weeks longer.
« Last Edit: July 17, 2016, 09:46:54 AM by Rob Dekker »
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JayW

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Re: The 2016 melting season
« Reply #3405 on: July 17, 2016, 11:03:30 AM »
Thanks for all the feedback.  :)  I certainly have no problem with anyone challenging my claims.

I've been asked on a couple of occasions why I use the VIIRS imagery from the university of Alaska fairbanks and the university of Colorado.   It's because I an watching the weather/ice interaction.  Worldview removes too many clouds, and stitches together images that come from different times.  Every VIIRS image I use is a single shot.  That way when I make an animation, I know the movement is relative to the time.

The VIIRS instrument had a very wide field of view, this allows the SUOMI satellite to image an area like 6-8 timrs a day, so features can be looked at multiple times per day.

First I'll address the time.  I'm very comfortable in saying that big block began breaking up between 0-2z on July 16.  Sorry Rob.  :)  this clearly is evident on these the three MODIS images in attachment 1.  The times are July 16 @ 202z, 337z, 512z. The crack is already visible by 202z.

I actually think the big block is getting shredded, and folks will be surprised by how unrecognizable it will be on its next appearance on Worldview.

Since I'm trying to prove myself, I'm going to revisit another point I was asked about.  And that is identifying a rain/snow line on VIIRS imagery using bands I01 - I02 - I03.

Second attachment is July 15/1140z until July 16/2217z.  Remember, there is always an unavoidable 12  hour "skip" between 0z and 12z with my VIIRS animations, it just doesn't image that area between those times. 

Two storms are shown, the first moves through dropping rain and snow. The second more powerful cyclone quickly moves in, third attachment is a shot of what I very strongly believe is a rain/snow line circled in red.

All MODIS and VIIRS imagery courtesy of the university of Alaska at fairbanks.
http://feeder.gina.alaska.edu

« Last Edit: July 17, 2016, 12:52:47 PM by JayW »
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Andreas T

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Re: The 2016 melting season
« Reply #3406 on: July 17, 2016, 11:29:48 AM »
IMB2015F http://imb.erdc.dren.mil/2015F.htm shows increase in snow height, this can sometimes have reasons other than falling snow but it fits with what you are showing, if my guessing of location of the buoy in your image is right.

echoughton

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Big Block Lives!
« Reply #3407 on: July 17, 2016, 12:06:31 PM »
YAY ATeam!

Big Block alive and well...the news of its demise has been greatly exaggerated. Enjoying this site immensely. And photos from buoy 14?

JayW

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Re: The 2016 melting season
« Reply #3408 on: July 17, 2016, 12:08:15 PM »
Thanks Andreas.  :)

I'm just trying to learn here, ALL critiques and criticisms are happily received.

In my opinion, the snow is also visible on AVHRR imagery.  These are labeled as "visible bands". I have circled in blue, my best guess at snow in attachment 2.

It's a very pretty storm by the way.

http://weather.gc.ca/satellite/satellite_anim_e.html?sat=hrpt&area=dfo&type=nir
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Jim Hunt

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Re: The 2016 melting season
« Reply #3409 on: July 17, 2016, 12:20:00 PM »
That wasn't Big Block.

With all due respect A-Team, it would only have taken you a click/scroll/click on my comment to get to the original VIIRS image at GINA and confirm that it did in fact reveal "Big Block split asunder" with a timestamp of "2016-07-16 12:22 UTC".
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Tigertown

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Re: The 2016 melting season
« Reply #3410 on: July 17, 2016, 12:45:15 PM »
The cyclone is going to leave the Beaufort with a lot more open water. When the clouds clear, we will be able to see and the sun will get into action and warm up whatever is cooled by the storm moving ice around and melting it. All the other floes that are compacted (in the proximity) will now have more room to move around. The compaction has really protected it up till now.

seaicesailor

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Re: The 2016 melting season
« Reply #3411 on: July 17, 2016, 01:08:57 PM »
Thanks Andreas.  :)

I'm just trying to learn here, ALL critiques and criticisms are happily received.

In my opinion, the snow is also visible on AVHRR imagery.  These are labeled as "visible bands". I have circled in blue, my best guess at snow in attachment 2.

It's a very pretty storm by the way.

http://weather.gc.ca/satellite/satellite_anim_e.html?sat=hrpt&area=dfo&type=nir

This is an amazing work Jay.
The hurricane-like shape reminds to the definition of polar lows, but these are smaller, typical in winter and winds above 35 knots, this one dragging no more than 25 knots.
The lowest pressure is not so deep, about 990 hpa, but the fact that it is surrounded by 'walls' of high pressures up to 1025 hpa makes it stronger than usual for its min pressure.
It will be bringing coldness to Beaufort and its CAB sector for the whole week! That can be a game changer I guess especially for the closed ice pack. 2015F will be telling, as Andreas noted it already might have gotten a nice amount of snow (~10 cm)
« Last Edit: July 17, 2016, 01:17:13 PM by seaicesailor »

Jim Hunt

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Re: The 2016 melting season
« Reply #3412 on: July 17, 2016, 01:32:42 PM »
The lowest pressure is not so deep, about 990 hpa, but the fact that it is surrounded by 'walls' of high pressures up to 1025 hpa makes it stronger than usual for its min pressure.

The lowest thus far is 986 hPa:

http://GreatWhiteCon.info/2016/07/the-mid-july-surf-forecast-for-the-beaufort-sea/#Jul-17
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Cate

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Re: The 2016 melting season
« Reply #3413 on: July 17, 2016, 02:14:45 PM »
Up-front apology if this doesn't belong here---it's not quite Arctic, as it's off the NE coast of Newfoundland. Can someone explain this phenom please---cause (wind? normal upwelling in the current?) and effect in terms of ice melt? It's an eddy of sea ice in the Labrador Sea, captured both on satellite and from a jet. Where else does this happen? Nares, Davis Strait....?

https://www.theweathernetwork.com/news/articles/sea-ice-hurricane-spotted-off-the-coast-of-newfoundland/70158/

Jim Hunt

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Re: The 2016 melting season
« Reply #3414 on: July 17, 2016, 02:20:42 PM »
2015F will be telling, as Andreas noted it already might have gotten a nice amount of snow (~10 cm)

Given the recent surface melting in the vicinity of 2015F, isn't it more likely that the snow surface sensor is detecting melt water rather than snow?

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2016-images/#CAB

Here's the latest temperature profiles from 2015F too:
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Jim Hunt

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Re: Big Block Lives!
« Reply #3415 on: July 17, 2016, 02:27:47 PM »
Big Block alive and well.

Big Block is smaller than it used to be.

Quote
And photos from buoy 14?

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2016-images/#OBuoy14

Note the melt ponds, and the fact that the AOFB in the background seems to have sunk a few cm recently.
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Ninebelowzero

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Re: The 2016 melting season
« Reply #3416 on: July 17, 2016, 02:52:08 PM »
Steadfast refusal here to get emotionally involved over particular lumps of ice.  :)

One might find oneself "in a world of hurt" as Jesse would say later in the season.










Paladiea

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Re: The 2016 melting season
« Reply #3417 on: July 17, 2016, 03:25:27 PM »
Whenever I feel down, I always listen to "Only Happy When It Rains" by Garbage. I think that song should be the theme for the season. ;)

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EgalSust

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Re: Big Block Lives!
« Reply #3418 on: July 17, 2016, 03:39:34 PM »

dnem

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Re: The 2016 melting season
« Reply #3419 on: July 17, 2016, 05:18:33 PM »
Hi Cate-  I suspect it's just a normal ocean eddy that has entrained some surface ice.  See link for general explanation of eddies.

https://www.whoi.edu/main/topic/currents--gyres-eddies

Cate

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Re: The 2016 melting season
« Reply #3420 on: July 17, 2016, 06:41:21 PM »
Hi Cate-  I suspect it's just a normal ocean eddy that has entrained some surface ice.  See link for general explanation of eddies.

https://www.whoi.edu/main/topic/currents--gyres-eddies

Cool link. And on that page there's a link to a video called "Warm Eddies in a Cold Sea" that focuses on the Labrador Current---so spot on! Thanks so much, dnem.

Michael Hauber

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Re: The 2016 melting season
« Reply #3421 on: July 17, 2016, 11:14:40 PM »
Interesting that the 925 hp temps are about the same as last year's July heat wave.  I did not think it was as bad looking at the charts.  The truly remarkable thing about last year though was the length of time that the temperature stayed near the 1980-2010 record temp line.
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FishOutofWater

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Re: The 2016 melting season
« Reply #3422 on: July 17, 2016, 11:51:51 PM »
There's a lot of interpretation going on here that, well, let us say, is imaginative. I appreciate A-Team's explanation of what goes into  the Worldview images. However, Jim's specific image from a specific satellite at a specific time is evidence that "big block" is on the way to becoming a slushy margarita mix. Wave action has shaken and stirred it. This is a great example of how waves speed up mixing and bottom melting turning apparently solid blocks of ice into slush.

As for the rain/snow line...there is no connection of the line in the imagery to the ongoing cloud motions in the  video loop. The line is unrelated to the weather.

By July the atmosphere doesn't have cold left stored up from winter. Lows over the Arctic have a temperature profile going from the surface to high levels of the troposphere that is consistent with uplift of surface air to higher levels of the atmosphere.

jdallen

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Re: The 2016 melting season
« Reply #3423 on: July 18, 2016, 12:03:41 AM »
Heck with the big block... have ya'll seen what the storm has done to the basin?

It's been torn to shreds.  Image from today, visible light, 1KM resolution.  Wrangel in the upper left hand corner.  Current storm center bottom center of the image.
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jdallen

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Re: The 2016 melting season
« Reply #3424 on: July 18, 2016, 12:19:15 AM »
Hmmm.  I think there's some confusion here.

I don't think the big block has split yet - at least it hadn't as of 2 days ago.  I think what you're looking at that split is quite a bit further west, and about 1/3 the size (last image).

Here's images - BB first.
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Nick_Naylor

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Re: The 2016 melting season
« Reply #3425 on: July 18, 2016, 12:25:18 AM »
Heck with the big block... have ya'll seen what the storm has done to the basin?

It's been torn to shreds.  Image from today, visible light, 1KM resolution.  Wrangel in the upper left hand corner.  Current storm center bottom center of the image.

Sure, but look at the NSIDC Extent - the basin is just a big block of solid ice! You can read whatever you want into that "satellite image." I just put my faith in scientific measurements! :o :o

mati

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Re: The 2016 melting season
« Reply #3426 on: July 18, 2016, 12:34:01 AM »
extent is becoming a usless measurement in the coming environment....
and so it goes

Nick_Naylor

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Re: The 2016 melting season
« Reply #3427 on: July 18, 2016, 12:36:50 AM »
They're all "useless" at times unless they're used wisely:)

Tigertown

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Re: The 2016 melting season
« Reply #3428 on: July 18, 2016, 12:42:25 AM »
extent is becoming a usless measurement in the coming environment....
I will second that emotion. Before long. Maybe a couple of weeks from now when open water is taking in insolation at the North Pole, it will be obvious how bad this season is.

Nick_Naylor

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Re: The 2016 melting season
« Reply #3429 on: July 18, 2016, 12:55:03 AM »
It's just one measurement - IMO possibly less valuable than usual this year because the ice is so broken up.
This is captured in the compactness measure of Area/Extent that Neven has elaborated on several times, for example here: http://neven1.typepad.com/blog/2016/06/2016-melting-momentum-part-2.html

For the time of year, 2016 is now at approximately record low compactness, i.e., there are lots of holes in the ice.

Andreas T

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Re: The 2016 melting season
« Reply #3430 on: July 18, 2016, 01:13:25 AM »
Hmmm.  I think there's some confusion here.

I don't think the big block has split yet - at least it hadn't as of 2 days ago.  I think what you're looking at that split is quite a bit further west, and about 1/3 the size (last image).
...
you might want to look again at what has been shown in the posts above, or just switch to 89GHz brightness temp on the 17th and then to AQUA visible  :-[ http://go.nasa.gov/29Rvw0m

but enough of one particular chunk of ice. At Barrow, the storm has brought back some ice to the shore (as expected). In the process some of it will have fallen victim to warm waters from the Chukchi following behind, we will see when the clouds clear

Ice Shieldz

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Re: The 2016 melting season
« Reply #3431 on: July 18, 2016, 01:17:39 AM »
Heck with the big block... have ya'll seen what the storm has done to the basin?

It's been torn to shreds . . .

"torn to shreds" might be a bit superlative.  Looks to me like the areas that were already rubble have been dispersed and broken up a bit more.  As others have indicated, with the right weather (sun and/or wind-induced thermal mixing) melting may seriously speed up.  All eyes on the CAB. :o

Jim Hunt

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Re: The 2016 melting season
« Reply #3432 on: July 18, 2016, 01:34:16 AM »
Enough of one particular chunk of ice.

For the avoidance of any doubt the BB split is even visible on AMSR2, as is much else:
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Michael Hauber

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Re: The 2016 melting season
« Reply #3433 on: July 18, 2016, 02:11:31 AM »
I just spotted that 2007 had a big block, similar size to this year's big block.  Its hard to tell what happens using ADS, but my guess is the block was mostly together until late July, it then broke up and came close to and mostly but not totally melted out by minimum.
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jdallen

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Re: The 2016 melting season
« Reply #3434 on: July 18, 2016, 02:19:32 AM »
Heck with the big block... have ya'll seen what the storm has done to the basin?

It's been torn to shreds . . .

"torn to shreds" might be a bit superlative.  Looks to me like the areas that were already rubble have been dispersed and broken up a bit more. 

Ah, perhaps a poor choice of words in hindsight.  Nonetheless, there appears to have been an non-trivial amount of dispersal, which I consider alarming, and expansion of open water in and along the ESS and Laptev.

As others have indicated, with the right weather (sun and/or wind-induced thermal mixing) melting may seriously speed up.  All eyes on the CAB. :o

Eyes on the CAB indeed.  The impact could be nominal, it could be "normal", or it could be extraordinary.  I'm not sure which yet.
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jdallen

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Re: The 2016 melting season
« Reply #3435 on: July 18, 2016, 02:23:48 AM »
Enough of one particular chunk of ice.

For the avoidance of any doubt the BB split is even visible on AMSR2, as is much else:
I concur, that the block you reference is the BB and may have split; I'll wait for visibility to return to confirm myself.

However, I don't think that is the same block as Jay was looking back up in #3405

That was my point.  I think people have been talking about two different blocks.
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vigilius

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Re: The 2016 melting season
« Reply #3436 on: July 18, 2016, 02:27:01 AM »
FWIW Here is most recent image I can see from 17 July centered on Lat 74.7928 x Long -146.6134. Looks like Big Block to me. Looks split? (Didn't look split two days ago, was under clouds yesterday) Thank you for letting me join the Forum's adopt-a-floe program and thanks to all for helping me to a front row seat at the ongoing catastrophe.
« Last Edit: July 18, 2016, 02:38:56 AM by vigilius »

seaicesailor

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Re: The 2016 melting season
« Reply #3437 on: July 18, 2016, 02:32:59 AM »
extent is becoming a usless measurement in the coming environment....
I will second that emotion. Before long. Maybe a couple of weeks from now when open water is taking in insolation at the North Pole, it will be obvious how bad this season is.
Will you consider the possibility that either CAB gets compacted or the volume will go to the upper limit of the predictions come November? Could it be that storm effects are negative for the ice only near the edges where real melt eventually happens (warm air from continents and Pacific, surface melting, insolation in open water, warm ocean currents, etc etc).


Tigertown

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Re: The 2016 melting season
« Reply #3438 on: July 18, 2016, 03:42:49 AM »
That's always possible, for what's left,season's end. I never have thought that there wouldn't be some fair amount left to re-compact and freeze.I don't think anytime before then,that the ice will get pushed together. If it opens up in time for the sun to have an influence I think there will be the heaviest damage down the middle ever, and that will really set things up for next year.

Rob Dekker

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Re: The 2016 melting season
« Reply #3439 on: July 18, 2016, 07:17:33 AM »
...
Every VIIRS image I use is a single shot.  That way when I make an animation, I know the movement is relative to the time.

The VIIRS instrument had a very wide field of view, this allows the SUOMI satellite to image an area like 6-8 timrs a day, so features can be looked at multiple times per day.

First I'll address the time.  I'm very comfortable in saying that big block began breaking up between 0-2z on July 16.  Sorry Rob.  :)  this clearly is evident on these the three MODIS images in attachment 1.  The times are July 16 @ 202z, 337z, 512z. The crack is already visible by 202z.
....
All MODIS and VIIRS imagery courtesy of the university of Alaska at fairbanks.
http://feeder.gina.alaska.edu

Thanks Jay, this is a good learning experience.
WorldView shows only one image per day, and it is hard to figure out which part of which image comes from which satellite.
That Gina feeder shows many more images (including multiple swats of Suomi and Modis each 12 hours) and for the fun of it, I used that to further determine when Big Block broke up (or more precisely when 3 pieces separated from Big Block) :

First image of the day (in the Gina Uni-Alaska feed) is this one from July 16, 00.19 UTC :
http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images/2016_07_16_00_19_jd198
It shows Big Block intact in the upper right hand corner.

Second image is from 5:12 UTC
http://feeder.gina.alaska.edu/modis-gina-alaska-naturalcolor-images/2016_07_16_05_12_jd198
with Big Block top-center, with a small crack visible.
Given the resolution, that crack must be a km wide or so, so you are right :
Big Block broke in the early morning of July 16, between 00:19 and 5:12 UTC.

Third image is from 10:41 UTC
http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images/2016_07_16_10_41_jd198
with the crack visible and widening, and

Forth image is from 12:22 UTC :
http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images/2016_07_16_12_22_jd198
where the skies are clear over Big Block, and the main fracture is clearly visible, and the part that split off breaking into 3 pieces.
That is the image that Jim posted on his blog (thanks Jim!).

The block in question is definitively A-team's Big Block (tracked since Feb, and surveyed for ice thickness in April), so there should not be any dispute that a large chunk of Big Block separated, and split into 3 pieces, while the remaining mother block is still one .. very .. big .. momma.

[edit] Remaining questions are :
(1) Where did you find this image :
http://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=1493.0;attach=32879;image
which you posted above (labeled Suomi July 16) which shows Big Block still in one piece, and what is the time stamp of this image ?

(2) What are these z-time numbers you use (202z, 337z, 512z) and how do they relate to UTC ?
« Last Edit: July 18, 2016, 07:35:47 AM by Rob Dekker »
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Re: The 2016 melting season
« Reply #3440 on: July 18, 2016, 07:47:18 AM »
FWIW Here is most recent image I can see from 17 July centered on Lat 74.7928 x Long -146.6134. Looks like Big Block to me. Looks split? (Didn't look split two days ago, was under clouds yesterday) Thank you for letting me join the Forum's adopt-a-floe program and thanks to all for helping me to a front row seat at the ongoing catastrophe.

Vigilius, welcome to the forum, and yes, I think you are right.
Big Momma (the remaining large piece of the July 16 break-off) has now split into 3 pieces herself.
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Re: The 2016 melting season
« Reply #3441 on: July 18, 2016, 07:56:30 AM »
Now that Big Block has broken into 6 pieces, joining the remaining MYI floes that are melting out in the Beaufort, let us look North, at the CAB. And, darn, it really does not look good there.

Lots of FYI and slush and Rubble North of the Beaufort.
Just a tiny bit of heat that makes it past the MYI flows in the Beaufort will create flash-melts and steep declines. Does not look good at all.
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Re: The 2016 melting season
« Reply #3442 on: July 18, 2016, 08:00:25 AM »
Okay FWIW here is a gif of Big Block from July 6 through 18, image centered on 74.55 x -147.54 yeah, I guess it is split (sob)

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Re: The 2016 melting season
« Reply #3443 on: July 18, 2016, 08:13:58 AM »
Now that Big Block has broken into 6 pieces, joining the remaining MYI floes that are melting out in the Beaufort, let us look North, at the CAB. And, darn, it really does not look good there.

Lots of FYI and slush and Rubble North of the Beaufort.
Just a tiny bit of heat that makes it past the MYI flows in the Beaufort will create flash-melts and steep declines. Does not look good at all.
I have the firm suspicion that the inflow of waters through the Bering is affecting or will affect this area.
Z stands for Zulu hour, the military way to say UTC or the same as the old GMT for practical purposes

Rob Dekker

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Re: The 2016 melting season
« Reply #3444 on: July 18, 2016, 08:30:27 AM »
I have the firm suspicion that the inflow of waters through the Bering is affecting or will affect this area.

Thanks Seaicesailor, but why do you think the waters through the Bering will affect the CAB area north of the Beaufort ?
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Re: The 2016 melting season
« Reply #3445 on: July 18, 2016, 09:39:53 AM »
It's just one measurement - IMO possibly less valuable than usual this year because the ice is so broken up.
This is captured in the compactness measure of Area/Extent that Neven has elaborated on several times, for example here: http://neven1.typepad.com/blog/2016/06/2016-melting-momentum-part-2.html

For the time of year, 2016 is now at approximately record low compactness, i.e., there are lots of holes in the ice.

With two days of added data, the 2016 trend line has shot up (a bit less on the CAMAS graph):
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JayW

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Re: The 2016 melting season
« Reply #3446 on: July 18, 2016, 10:59:46 AM »

The block in question is definitively A-team's Big Block (tracked since Feb, and surveyed for ice thickness in April), so there should not be any dispute that a large chunk of Big Block separated, and split into 3 pieces, while the remaining mother block is still one .. very .. big .. momma.

[edit] Remaining questions are :
(1) Where did you find this image :
http://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=1493.0;attach=32879;image
which you posted above (labeled Suomi July 16) which shows Big Block still in one piece, and what is the time stamp of this image ?

(2) What are these z-time numbers you use (202z, 337z, 512z) and how do they relate to UTC ?

Hi Rob,

Thanks.

That image was posted by slow wing, it was from Worldview, so I haven't a clue. Apologies, I looked through every image on the GINA site, MODIS and VIIRS, and didn't see that shot.

seaicesailor kindly explained z time.

I stand by every word I have posted, but I'm done talking about that one piece of ice.  I shouldn't even post any of my observations, as they seem to have caused the forum to go off track, for that I apologize.  I thought I was simply reporting what I saw, and since I didn't use worldview, I was called into question.

I still say that it can snow in the arctic in July, and the storm did bring snow to some areas.  This is the last I'll post on any of this, and will not clog up the thread with my counterproductive interpretations.

« Last Edit: July 18, 2016, 12:32:35 PM by JayW »
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Jim Hunt

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Re: The 2016 melting season
« Reply #3447 on: July 18, 2016, 11:22:27 AM »
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Jim Hunt

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Re: The 2016 melting season
« Reply #3448 on: July 18, 2016, 11:25:42 AM »
This is the last I'll post on any of this, and will not clog up the thread with my counterproductive interpretations.

Please don't do that. Personally I find your contributions very interesting.
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Re: The 2016 melting season
« Reply #3449 on: July 18, 2016, 11:57:57 AM »

Z stands for Zulu hour, the military way to say UTC or the same as the old GMT for practical purposes

Actually, the Z stands for "Zero" and is the offset from UTC.

If I wanted to write the time on my computer, I could write it as 10:52+0100 because it's 10:52 in British Summer Time, which is UTC+1. If I was getting time from my server, it would be 09:52:+0000 because it's on UTC. You could also write this as 09:52Z because the offset from UTC is Zero.

In the NATO phonetic alphabet, the name for Z is Zulu, so this time is referred to as Zulu time, but the Zulu stands for Z (not vice-versa) and the Z stands for Zero.

A bit of a digression, I admit, but maybe someone will find it interesting.