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Rich

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Re: The 2019 melting season
« Reply #4850 on: July 28, 2019, 09:52:28 AM »
+1

Killian

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Re: The 2019 melting season
« Reply #4851 on: July 28, 2019, 10:07:25 AM »
Appears that the Nares is sending ice south again

Responding bc I noticed this days ago, but your post implies it is very recent. Using the movie function via worldview, it seems the ice reversed back south roughly on the 15th.

FYI.

FYI, this is BS.

The surface current in NS picked up 26.07.

Nope. S from 22 > 23. S from 23 > 24 (obscured, have to look further south in the channel.) S from 24 > 25. S from  25 > 26. S from 26 > 27.

25th
https://worldview.earthdata.nasa.gov/?p=arctic&l=MODIS_Terra_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_Bands367,MODIS_Aqua_CorrectedReflectance_Bands721(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor(hidden),Reference_Labels(hidden),Reference_Features(hidden),Coastlines(hidden)&t=2019-07-25-T00%3A00%3A00Z&z=3&v=-594910.7948410034,-1030006.5078590395,-201694.79484100343,-834422.5078590395&ab=off&as=2019-07-07T00%3A00%3A00Z&ae=2019-07-25T00%3A00%3A00Z&av=1.5&al=true

26th
https://worldview.earthdata.nasa.gov/?p=arctic&l=MODIS_Terra_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_Bands367,MODIS_Aqua_CorrectedReflectance_Bands721(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor(hidden),Reference_Labels(hidden),Reference_Features(hidden),Coastlines(hidden)&t=2019-07-26-T00%3A00%3A00Z&z=3&v=-594910.7948410034,-1030006.5078590395,-201694.79484100343,-834422.5078590395&ab=off&as=2019-07-07T00%3A00%3A00Z&ae=2019-07-25T00%3A00%3A00Z&av=1.5&al=true

27th
https://worldview.earthdata.nasa.gov/?p=arctic&l=MODIS_Terra_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_Bands367,MODIS_Aqua_CorrectedReflectance_Bands721(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor(hidden),Reference_Labels(hidden),Reference_Features(hidden),Coastlines(hidden)&t=2019-07-27-T00%3A00%3A00Z&z=3&v=-594910.7948410034,-1030006.5078590395,-201694.79484100343,-834422.5078590395&ab=off&as=2019-07-07T00%3A00%3A00Z&ae=2019-07-25T00%3A00%3A00Z&av=1.5&al=true
« Last Edit: July 28, 2019, 10:17:58 AM by Killian »

Sterks

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Re: The 2019 melting season
« Reply #4852 on: July 28, 2019, 10:14:48 AM »
Apart from the Greenland ridge getting a boost, there’s an event forecasted by EC 6 days ahead, this apparently weak inoffensive storm but that, being compact in size and surrounded by a background of high pressure, its isobars mean pretty strong winds for a day or two, impacting on the most broken part of the Pacific edge. This means churning floes and accelerating their demise.

We’ll see how and if it pans out. For the rest, a lot of movement but no pattern especially good or bad for the pack once the current anticyclone leaves the Arctic in two days.
Also noting the ESS suffering severe winds right now.

The pic corresponds to ECMWF +144h SLP anomaly.

oren

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Re: The 2019 melting season
« Reply #4853 on: July 28, 2019, 10:38:00 AM »
A notable divergence in Wipneus' area calculations between the slopes in area calculations using NSIDC (25 km) vs. both Jaxa (10 km) and UH (3 km) continues to increase. What does it signify? Wide scale dispersion? A difference in the sensors?
When the pack has been dispersed, there are broken areas that the hi res don’t pick as low concentration ( as they are able to pick open water that the lo res thinks is lower concentration). So when it is compacted, hi res does not see local increase of concentration, lo res does,
Second, NSIDC is much more sensitive to melt ponds, and there was some refreeze over Beaufort and CAB.
So I think it signifies both indeed.
This divergence is inevitable at this time of year I think. If you look at the multi-sensor Arctic Basin area chart by Wipneus and read the scales carefully, you will see that NSIDC area tracks much lower than JAXA and UH, despite starting from the same area in March and ending with roughly the same area in September. So initially NSIDC diverges down, and towards the end diverges up. NSIDC being more sensitive to meltwater makes sense as the explanation.
Note: I just realized the magnitude of this divergence today for some reason. Guess I haven't been paying attention all these years.

Killian

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Re: The 2019 melting season
« Reply #4854 on: July 28, 2019, 11:06:28 AM »

7/27/2012 (<-- edit) stood at 6.37M km sq. on this date, a big drop of 140k.
7/26/2019 stands at 6.39M km sq. 2019 needs a drop > 20k km sq. for a record low on this date.

Pretty likely... Let's say -50k

Well, it wasn't huge, but huger than my 50k. 7/26/2019 stands at 6.29M km sq., rounded, after about a 96k drop.

7/28/2012 stood at 6.29M km sq. on this date , a drop of 80k.
7/27/2019 stands at 6.29M km sq. 2019 needs a drop > 0k km sq. for a record low on this date.

Well, shucks, I think we may just get there! Still, like yesterday, it looks like there should be expansion of extent everywhere that matters, all the way from Alaska to around Siberia and over to Svalbard except the Bering Strait into Chukchi. Are the winds too weak to shove the ice around? The winds off of Greenland into the basin look like they could really get some compaction going, but there's ice there, not open water. The caveat would be all the space between floes, I suppose.

I can't see a century day for the 28th, but since it looks not unlike yesterday, let's say -80+/-15. If those winds off of northern Greenland shove the ice toward the Pole like happened last year (iirc), opening up a wide swath of ocean there, then the number could be a big drop, but it'll rebound later... like last year.

-------------------------

8/10/2012 stood at 4.94M km sq. on this date.
2019 needs an average daily drop of > 92.29k km sq. for a record low on this post-GAC date. (14 days )
****Edit: Database error.

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 62.16k km sq. for a record low on this date. (50 days)
« Last Edit: July 29, 2019, 12:08:04 PM by Killian »

blumenkraft

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Re: The 2019 melting season
« Reply #4855 on: July 28, 2019, 11:14:01 AM »
Killian, i replied to your post in the NS thread.

“You are not entitled to your opinion. You are entitled to your informed opinion. No one is entitled to be ignorant.”

blumenkraft

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Re: The 2019 melting season
« Reply #4856 on: July 28, 2019, 11:15:04 AM »
@Rich
@Sterks

Thanks, guys! :)
“You are not entitled to your opinion. You are entitled to your informed opinion. No one is entitled to be ignorant.”

Shared Humanity

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Re: The 2019 melting season
« Reply #4857 on: July 28, 2019, 03:44:28 PM »
Is that you B_L? If that's so, I am happy you are back!

Yep, that's me. Not sure i'm fully back, but since Arsedolph Shittler isn't around anymore as it seems there is some space for me again i guess. ;)

Thanks, Oren! I'm glad you feel that way. :)

Not sure who AS is but I am also glad to see you.

Aleph_Null

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Re: The 2019 melting season
« Reply #4858 on: July 28, 2019, 04:34:15 PM »
Just a word about the left and right arrow keys in Worldview, which have greatly enhanced my Arctic experience: they take you back or forward a day. The first time you load a day, the screen turns black for a moment. After that you can zoom in anywhere and animate with the arrow keys! The visual temporal data is richer for my understanding than anything else I see. It's all on the move up there.

One more thing: Worldview apparently rewrites its own URL in the address bar. That means you can just forward the URL and the recipient will see the same thing you had on screen. Most awesome! Here, for instance, you can see > 1 km2 gaps in the CAB at 82.5N:

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor,Graticule,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2019-07-28-T00%3A00%3A00Z&z=3&v=-613836.8177134156,580491.625339504,-449996.8177134156,666891.625339504&ab=off&as=2019-06-15T00%3A00%3A00Z&ae=2019-06-20T00%3A00%3A00Z&av=3&al=true

« Last Edit: July 28, 2019, 04:44:48 PM by Aleph_Null »

Killian

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Re: The 2019 melting season
« Reply #4859 on: July 28, 2019, 04:55:55 PM »
A notable divergence in Wipneus' area calculations between the slopes in area calculations using NSIDC (25 km) vs. both Jaxa (10 km) and UH (3 km
When the pack has been dispersed, there are broken areas that the hi res don’t pick as low concentration... So when it is compacted, hi res does not see local increase of concentration...
This divergence is inevitable at this time of year I think...

Note: I just realized the magnitude of this divergence today for some reason. Guess I haven't been paying attention all these years.

Odd, no, that NSIDC ASIE is higher than JAXA and NSIDC ASIA is lower?

be cause

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Re: The 2019 melting season
« Reply #4860 on: July 28, 2019, 05:16:52 PM »
Hi Aleph .. if you hover over 'days' you get options for months and years too .. it took me a year to notice this so may be helpful to others beginning their Arctic watching .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

blumenkraft

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Re: The 2019 melting season
« Reply #4861 on: July 28, 2019, 05:20:03 PM »
Not sure who AS is but I am also glad to see you.

Thanks, SH! Means a lot. :)
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Davidsf

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Re: The 2019 melting season
« Reply #4862 on: July 28, 2019, 05:20:57 PM »
Petm I like the side-by-side animation you posted. Sorry for dumb question, but since you plan to post more of these, is that a comparison of 2012 and 2019? Or a different comparison? Thanks
« Last Edit: July 28, 2019, 05:37:33 PM by Davidsf »

aslan

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Re: The 2019 melting season
« Reply #4863 on: July 28, 2019, 05:41:40 PM »
Just a word about the left and right arrow keys in Worldview, which have greatly enhanced my Arctic experience: they take you back or forward a day. The first time you load a day, the screen turns black for a moment. After that you can zoom in anywhere and animate with the arrow keys! The visual temporal data is richer for my understanding than anything else I see. It's all on the move up there.

One more thing: Worldview apparently rewrites its own URL in the address bar. That means you can just forward the URL and the recipient will see the same thing you had on screen. Most awesome! Here, for instance, you can see > 1 km2 gaps in the CAB at 82.5N:

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor,Graticule,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2019-07-28-T00%3A00%3A00Z&z=3&v=-613836.8177134156,580491.625339504,-449996.8177134156,666891.625339504&ab=off&as=2019-06-15T00%3A00%3A00Z&ae=2019-06-20T00%3A00%3A00Z&av=3&al=true

Ice is badly damaged in the sector, with significant gaps up to 83°N and ice loosing cohesion up 85°N. This is also reflected in the ice concentration map of yesterday. Too bad we don't have good data for sea state in Arctic. There is a wave train propagating toward this arm of ice, but we don't have more information. This is even showing at Prudhoe Bay, with an ongoing surge. https://tidesandcurrents.noaa.gov/waterlevels.html?id=9497645 Nothing remarkable, excepted that the wave train is not going toward the coast... Ice drift is quite impressive also, movement in one day seems to reach more than 30 km for some features.... We will see what happen in the next days, but significant melt is likely to continue on this side of the Arctic.

UCMiami

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UCMiami

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Re: The 2019 melting season
« Reply #4865 on: July 28, 2019, 06:06:31 PM »
No idea what one calls this pattern but 250 hPa on nullschool is pretty impressive! (or a mess if you are looking for a nice rational jet stream!!)
https://earth.nullschool.net/#current/wind/isobaric/250hPa/orthographic=-64.39,88.54,568

Milwen

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Re: The 2019 melting season
« Reply #4866 on: July 28, 2019, 06:39:49 PM »
HYCOM - Arctic ice thickness (CICE) model - July 29 - August 4


Slim

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Re: The 2019 melting season
« Reply #4867 on: July 28, 2019, 10:22:15 PM »
No idea what one calls this pattern but 250 hPa on nullschool is pretty impressive! (or a mess if you are looking for a nice rational jet stream!!)
https://earth.nullschool.net/#current/wind/isobaric/250hPa/orthographic=-64.39,88.54,568

Does anyone have a picture of what it should look like, just for those of us who don't exactly know. I'm assuming much more tight and circular?

Grubbegrabben

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Re: The 2019 melting season
« Reply #4868 on: July 28, 2019, 10:25:09 PM »
No idea what one calls this pattern but 250 hPa on nullschool is pretty impressive! (or a mess if you are looking for a nice rational jet stream!!)
https://earth.nullschool.net/#current/wind/isobaric/250hPa/orthographic=-64.39,88.54,568

Does anyone have a picture of what it should look like, just for those of us who don't exactly know. I'm assuming much more tight and circular?

Use the link but flip the globe and look at the south pole.

oren

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Re: The 2019 melting season
« Reply #4869 on: July 28, 2019, 10:31:50 PM »
Quote
Odd, no, that NSIDC ASIE is higher than JAXA and NSIDC ASIA is lower?
When you think of it logically it makes sense. NSIDC has coarse resolution and phantom coastal ice, JAXA and UH have better grids and a better sensor, so show a lower extent. OTOH NSIDC suffers much more from wet surfaces, so undercounts area.
But to be honest, my intuition was completely off about this. So I did find it odd.

Steven

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Re: The 2019 melting season
« Reply #4870 on: July 28, 2019, 11:09:18 PM »
Quote
Odd, no, that NSIDC ASIE is higher than JAXA and NSIDC ASIA is lower?
When you think of it logically it makes sense. NSIDC has coarse resolution and phantom coastal ice, JAXA and UH have better grids and a better sensor, so show a lower extent. OTOH NSIDC suffers much more from wet surfaces, so undercounts area.

Wet surfaces are not the only reason for the sea ice area differences.  Even in Autumn, when there should be practically no wet surfaces anymore, NSIDC sea ice area is still substantially lower than UH AMSR2 area.  The graph below shows the difference between them, using 2013-2018 averages.



Here is a similar graph for extent rather than area:

UCMiami

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Re: The 2019 melting season
« Reply #4871 on: July 28, 2019, 11:19:31 PM »
Steven - can you clarify your labeling on the two graphs - have you in fact reversed the operation or just made and error in the label? As it stands it appears NSIDC records greater extent than UH but less area. I would expect the variance to be the same NSIDC having less area and less extent than UH.

aslan

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Re: The 2019 melting season
« Reply #4872 on: July 28, 2019, 11:24:57 PM »
No idea what one calls this pattern but 250 hPa on nullschool is pretty impressive! (or a mess if you are looking for a nice rational jet stream!!)
https://earth.nullschool.net/#current/wind/isobaric/250hPa/orthographic=-64.39,88.54,568

Does anyone have a picture of what it should look like, just for those of us who don't exactly know. I'm assuming much more tight and circular?

Usually yes, but seeing polar jet making wild loops is not unusual per se in the NH this said. So I am not sure that the mean will help you, but it's the attached map. I think it is worth emphazing that it is normal for the jet to undulate. And the tropical heating has a huge influence on the jet.  And it was worst at some point in the precedent years. This said this year the jet is definitively weird again this year, Arctic is not helping, and tropics are marching northward.

Steven

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Re: The 2019 melting season
« Reply #4873 on: July 28, 2019, 11:59:40 PM »
Steven - can you clarify your labeling on the two graphs - have you in fact reversed the operation or just made and error in the label? As it stands it appears NSIDC records greater extent than UH but less area. I would expect the variance to be the same NSIDC having less area and less extent than UH.

There's nothing wrong with the graphs as far as I see.  Note that NSIDC extent is greater than UH extent.   That may seem counter-intuitive, but there are actually good reasons for it, as discussed by Oren upthread (see Reply #4868).

UCMiami

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Re: The 2019 melting season
« Reply #4874 on: July 29, 2019, 12:23:43 AM »
Steven - the question is that based on the labels on the two graphs the relationship is as follows:
Extent
NSIDC is greater than UH

Area
UH is greater than NSIDC

I would have expected that whatever the methodologies inherent in the two systems, their bias would be the same: UH would be greater in both area and extent or it would be less in both. That they would reverse is very surprising and that is why I questioned the labels.

I expected UH extent to be greater, but also expect UH area to be greater for the same reason

petm

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Re: The 2019 melting season
« Reply #4875 on: July 29, 2019, 01:09:43 AM »
Petm I like the side-by-side animation you posted. Sorry for dumb question, but since you plan to post more of these, is that a comparison of 2012 and 2019? Or a different comparison? Thanks

They are both 2019. The one on the right is the original version. The one on the left is a smoothed version. Smoothing was done using a 5-day lagging median (the median concentration of each pixel of the 5 days leading up the the specified date).

Side by side of 2019 vs. 2012 is a good idea too.

sark

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Re: The 2019 melting season
« Reply #4876 on: July 29, 2019, 04:10:51 AM »
No idea what one calls this pattern but 250 hPa on nullschool is pretty impressive! (or a mess if you are looking for a nice rational jet stream!!)
https://earth.nullschool.net/#current/wind/isobaric/250hPa/orthographic=-64.39,88.54,568

Does anyone have a picture of what it should look like, just for those of us who don't exactly know. I'm assuming much more tight and circular?

Meridional wind anomaly year to date:
I am not a scientist

oren

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Re: The 2019 melting season
« Reply #4877 on: July 29, 2019, 04:15:27 AM »
Steven - the question is that based on the labels on the two graphs the relationship is as follows:
Extent
NSIDC is greater than UH

Area
UH is greater than NSIDC

I would have expected that whatever the methodologies inherent in the two systems, their bias would be the same: UH would be greater in both area and extent or it would be less in both. That they would reverse is very surprising and that is why I questioned the labels.

I expected UH extent to be greater, but also expect UH area to be greater for the same reason
UCMiami, Steven's labels are not wrong. The results are counter-intuitive, I had the same intuition as yours, but the reality is NSIDC extent is biased upward while NSIDC area is biased downward. In both cases, AMSR2 hits closer to the physical reality.

subgeometer

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Re: The 2019 melting season
« Reply #4878 on: July 29, 2019, 04:17:19 AM »
8C in Eureka on a north wind. Clear skies and warm air taking over most of the CAB and CAA.

The area north of Greenland will get an absolute roasting in coming days. with the Lincoln Sea having average temps near 4C till Friday, including 2 days at in a row where its 5 or 6C for 12hours at a time, and even warmer by the coast. Stiff breezes up Nares Strait and off Greenland will ensure plenty of that heat  meets the the ice.

I've included the GFS 5 day average forecast, as well as EC/WindyTv forecasts for temps and wind speed on Wednesday(ie in 2 days), with a worldview image of the area yesterday, where I've brought up the contrast for a section to show the distressed state of the ice there already. Combined with the crack widening under influence of continuing southerly winds, this area is a real worry

subgeometer

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Re: The 2019 melting season
« Reply #4879 on: July 29, 2019, 04:27:36 AM »
Hi Aleph .. if you hover over 'days' you get options for months and years too .. it took me a year to notice this so may be helpful to others beginning their Arctic watching .. b.c.

The Worldview URLs also contain a TIME parameter whose value is the date shown. You can change that in the browser searchbar or via a script to get to the date you want. (My own script is currently broken, as they changed format from year and daynumber recently, when I fix it I'll post on the programming thread)

Iain

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Re: The 2019 melting season
« Reply #4880 on: July 29, 2019, 04:48:22 AM »
CAA - There is cracking in the landfast ice all the way to the CAB. That's early, but not unprecedented. As near as I can, visibility permitting, the same event happend on these dates in the recent past:

2018 Aug 15
2017 Aug 22
2016 Between July 30 and Aug 04 (thick cloud)
2015 Jul 31
2014 Sept 12
2013 between Aug 11 and Aug 22 (thick cloud)
2012 July 28
"If I have seen further than others, it is by standing upon the shoulders of giants." Isaac Newton

tzupancic

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Re: The 2019 melting season
« Reply #4881 on: July 29, 2019, 05:06:57 AM »
First off, I think that the observation of landfast ice melt off of the Northeast coast of Greenland is relevant to the current 2019 Artic Sea Ice melting season discussion (to pre-empt inevitable comments from forum members who would suggest that this particular subject ought to be discussed somewhere else.)

Turns out, I have followed the annual melting off of the Northeast coast of Greenland with some interest for a number of years now. What I have observed is that this large chunk of ice is particularly resistant to dispersion and melting. It has been a very interesting element of the melting season to track.

In particular, there appears to be an underwater geologic feature that stabilizes the ice off the coast of Northeast Greenland such that going back on Worldview one will see that some big chunk of ice inevitably persists here every year. 

It now looks like some significant dispersion events are beginning to happen here.

I suggest that it will be interesting to see what happens to this ice as the current melting season progresses.
img]

UCMiami

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Re: The 2019 melting season
« Reply #4882 on: July 29, 2019, 05:10:15 AM »
Steve and Oren - thanks. It is counter-intuitive! Hence my restating the same question in two posts!

I guess it gets into the basic difference between area which requires either system to deal at a pixel level and extent which is percentage based on grid size.

All of our data sources for area, extent, and volume really are only consistent unto themselves so I guess it doesn't really signify, but it is an odd circumstance that the variance between two source for different measures flips from negative to positive.

subgeometer

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Re: The 2019 melting season
« Reply #4883 on: July 29, 2019, 06:03:42 AM »
Ice in Beaufort Sea 23-28 July. Melting as fast as the CAB can export, if not faster. JAXA lost another 100K today, a day ahead of 2012 for now, though the Bremen extent graph looks a lot worse, with 2012 apparently days behind

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Re: The 2019 melting season
« Reply #4884 on: July 29, 2019, 06:05:15 AM »
It seems to me incredible the way the whole Arctic sea ice has moved away from Canada & Greenland.
With the high temperatures that we are having there, should we expect some melting there? It is the place where we have the thickest ice.
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.

oren

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Re: The 2019 melting season
« Reply #4885 on: July 29, 2019, 06:27:14 AM »
Some kind of Transpolar movement is back upon us. If this remains sustained big trouble would follow, but hopefully the weather will change before the ice mass moves into the Atlantic killing zones.

subgeometer

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Re: The 2019 melting season
« Reply #4886 on: July 29, 2019, 06:43:44 AM »
A gif of a region of the pack north of the ESS. The aquare is centred at 82N, 169E and spans about 20 degrees of longitude from top right to bottom left. It shows melt proceeding and a highly mobile pack. I get the impression that collapsing rubble is spreading in the gaps closing them to a degree - maybe this kind of process is part of what is causing the odd area numbers.

I left out some days as they were totally filled with cloud, using the 22nd, 25th, and 27-9 July. I doubled up the start day so it pauses there a bit

jdallen

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Re: The 2019 melting season
« Reply #4887 on: July 29, 2019, 08:14:00 AM »
It seems to me incredible the way the whole Arctic sea ice has moved away from Canada & Greenland.
With the high temperatures that we are having there, should we expect some melting there? It is the place where we have the thickest ice.
I'd expect a slightly higher decrease in area, and moderate decrease in volume/thickness.  I'm not expecting this year will be able to apply enough heat to destroy it.
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jdallen

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Re: The 2019 melting season
« Reply #4888 on: July 29, 2019, 08:15:09 AM »
Some kind of Transpolar movement is back upon us. If this remains sustained big trouble would follow, but hopefully the weather will change before the ice mass moves into the Atlantic killing zones.
Mostly it looks like it will pile up against N. Greenland, and possibly Svalbard/Fram.
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meddoc

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Re: The 2019 melting season
« Reply #4889 on: July 29, 2019, 08:35:16 AM »
There's no Point in posting HYCOM, as they switched from ArCc to Glb Models since about 2017. Especially when making Comparisons.
Glb seems to indicate much less thicker Ice than the previously used ArCc Model.

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Re: The 2019 melting season
« Reply #4890 on: July 29, 2019, 08:49:35 AM »
Some kind of Transpolar movement is back upon us. If this remains sustained big trouble would follow, but hopefully the weather will change before the ice mass moves into the Atlantic killing zones.

There is definitely some high-octane wind aided Atlantic export in the forecast window. Through the Fram it starts slowly Friday and builds steadily through the weekend up to 20+ knot tail winds at the end of the 10 day window.

Always a chance that the forecast won't materialize, but they have been very good in general.

Thanks for the transport maps. They're excellent.

grixm

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Re: The 2019 melting season
« Reply #4891 on: July 29, 2019, 09:00:07 AM »
There's no Point in posting HYCOM, as they switched from ArCc to Glb Models since about 2017. Especially when making Comparisons.
Glb seems to indicate much less thicker Ice than the previously used ArCc Model.

Interesting, that can explain the question I've had for a while on why 2012 is so far ahead of 2019, even though on PIOMAS they are roughly tied.

bbr2314

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Re: The 2019 melting season
« Reply #4892 on: July 29, 2019, 09:10:34 AM »
There's no Point in posting HYCOM, as they switched from ArCc to Glb Models since about 2017. Especially when making Comparisons.
Glb seems to indicate much less thicker Ice than the previously used ArCc Model.

Interesting, that can explain the question I've had for a while on why 2012 is so far ahead of 2019, even though on PIOMAS they are roughly tied.
2019 is ahead of 2012 in PIOMAS and every other data set...

Killian

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Re: The 2019 melting season
« Reply #4893 on: July 29, 2019, 09:58:06 AM »
I can't see a century day for the 28th, but since it looks not unlike yesterday, let's say -80+/-15.

*Juuuust* missed it! -98,213 km2! Snickerdoodles!

Quote
7/28/2012 stood at 6.29M km sq. on this date , a drop of 80k.
7/27/2019 stands at 6.29M km sq. 2019 needs a drop > 0k km sq. for a record low on this date.

7/29/2012 stood at 6.20M km sq. on this date , a drop of 80k.
7/28/2019 stands at 6.19M km sq. 2019 needs an increase of < 10k km sq. for a record low on this date.

Analysis:

Going out on a limb here and saying century drop! "K-k-k," as they say in Korea (sound of snickering), given the ice being shoved off Greenland - as previously suspected! To wit:

Quote
If those winds off of northern Greenland shove the ice toward the Pole like happened last year (iirc), opening up a wide swath of ocean there, then the number could be a big drop

So, we got a bit more than I expected, but not a huge number. That seems to be coming for the 29th. Or is it? According to NullSchool wind patterns forthe 29th (UTC):

CAA/N. Greenland: Wind-aided compaction
Far western Canada:  Wind-aided expansion
N. Alaska, Bering Strait:  Wind-aided compaction
Almost all of Siberian coast:  Wind-aided expansion
Fram/Svalbard: Strong wind-aided compaction
East of Svalbard to W. Russian coast: Neutral to wind-aided expansion

Pretty mixed. But then there's all the heat. Literally throughout the Arctic basin. Surface melt is second to bottom melt, but there's all sorts of winds going every which way which should be getting water moving to at least some degree where there's space between floes, and certainly around the edges of the pack.

So, I'm giving priority to the winds coming off of Greenland, over the CAA and up the Fram/over Svalbard and calling a solid -120k +/-15k.
 
-------------------------

Quote
8/10/2012 stood at 4.94M km sq. on this date.
2019 needs an average daily drop of > 89.87k km sq. for a record low on this post-GAC date. (15 days <-- The previous number was in error. Or this one is. Whatever...)

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 62.16k km sq. for a record low on this date. (50 days)

8/10/2012 stood at 4.94M km sq.
2019 needs an average daily drop of > 96.15k km sq. for a record low on this post-GAC date. (13 days)

***Edit: Sorry, misreading my own spreadsheet. Today there's 6.19M km sq. there are 13 days remaining. So, starting with tomorrow the needed loss is 96.15/day. I was looking at today's needed drop... goofy. Also had my day numbering wrong.***
-------------------------------------------------------
9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 61.43k km sq. for a record low on this date. (49 days)

Note about this. The decline is useful to watch, IMO, because the daily decrease from Sept. 1 ~ Sept. 15th (the low date in '12) is only 20k, and, naturally, much smaller the closer it gets to the 15th low. Of course we can all eyeball that '19 is close to '12, but this gives us the actual numbers we need to be seeing.

That huge drop of 1,090 km sq (121k km sq/day) from the 2nd to the tenth is the first hurdle. If '19 comes at higher extent to that with any significance at all, I see zero chance of a new record because, as has been stated, researchers have suggested the June insolation is a key correlation with Sept. minima, but also that the GAC's effects lingered long after the storm by stirring up warmer deep waters. Thus, we see the broad, deep curve at the end of the season in 2012. At least, that's how I interpret it.

There is speculation the record June temps are going to translate/are translating into extended melt effects. I agree. Can it match the GAC effect? If '19 is below 2012 on the 10th, I think we can safely say "yes" to that. Whether that will also overcome that long, slumping curve at the bottom, well... Right now, with the the nastiness going on with France's little export, all the little cyclones, et al., it's going to be interesting!
« Last Edit: July 29, 2019, 12:04:32 PM by Killian »

Killian

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Re: The 2019 melting season
« Reply #4894 on: July 29, 2019, 10:02:34 AM »
It seems to me incredible the way the whole Arctic sea ice has moved away from Canada & Greenland.

Maybe. As I said might happen yesterday, that's wind effect. Had a big move like that last year and it slammed right back into the coast in, like, 2 days? Some melt, but that compaction is going to pile ice up, too, so maybe not too much...?

grixm

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Re: The 2019 melting season
« Reply #4895 on: July 29, 2019, 10:35:46 AM »
There's no Point in posting HYCOM, as they switched from ArCc to Glb Models since about 2017. Especially when making Comparisons.
Glb seems to indicate much less thicker Ice than the previously used ArCc Model.

Interesting, that can explain the question I've had for a while on why 2012 is so far ahead of 2019, even though on PIOMAS they are roughly tied.
2019 is ahead of 2012 in PIOMAS and every other data set...

Which is precisely why it's strange that it's far behind in DMI's volume model (which uses HYCOM thickness)

iceman

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Re: The 2019 melting season
« Reply #4896 on: July 29, 2019, 11:05:45 AM »
Some kind of Transpolar movement is back upon us. ....

Net for the pack as a whole, that's the most rotation I've seen all season.

oren

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Re: The 2019 melting season
« Reply #4897 on: July 29, 2019, 11:07:13 AM »
grixm, it's not strange if you consider that DMI's volume is extremely unreliable. I prefer to ignore it completely.
On the other hand, bbr's statement is not true. 2019 is slightly behind 2012 for NSIDC area.

bluice

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Re: The 2019 melting season
« Reply #4898 on: July 29, 2019, 11:24:27 AM »
Right now it's uncertain if 2019's lead in extent will be enough to stay ahead of 2012 because of huge August melt caused by the 2012 GAC. Average melt won't suffice for the record, but then again there hasn't been much average melt this season.

To look this from another perspective, if an event comparable to GAC occurred also this year, 2019 would take the record easily. The consensus here seems to be that ice is badly enough preconditioned to make this possible.
In PIOMAS we trust

VeganPeaceForAll

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Re: The 2019 melting season
« Reply #4899 on: July 29, 2019, 11:47:28 AM »
Here, in this link is a thorough Arctic weather update from meteorologist Nick Humphrey:

(Just an excerpt, read the full update on the link):

Quote
Highly anomalous heat from Europe will surge over Greenland surrounding areas Monday, peaking Tuesday-Thursday before decreasing in intensity over the weekend. This will cause a rapid rise in Greenland surface ice melt extent and more rapid Arctic sea ice losses.

Also note a significant cool air mass for late-July/early August will surge across Scandinavia, Eastern Europe and western Russia this week. Sweden, Norway and Finland just saw some of their hottest temperatures on record.

(...)

As I showed in my previous Arctic post, in addition to heat causing widespread surface melt on the Greenland Ice Sheet and additional sea ice melting, a Pacific to Atlantic windflow pattern will be favorable to pulling sea ice away from the Canadian Archipelago and north coast of Greenland. Open water is likely to grow north of the coast of Greenland and farther to the West. This is concerning because it means the waters locally can warm significantly and the entire thin ice area will be more vulnerable to cyclones later in August and September.

Full update: Arctic Forecast for Heat Wave This Week