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Freegrass

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The 2021 melting season
« on: March 15, 2021, 05:09:17 AM »
I saw Juan's numbers just now, and it looks like it's time to open up a new melting season thread.

Lets start off with HYCOM's overview of the past 12 months, including salinity.
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miki

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Re: The 2021 melting season
« Reply #1 on: March 15, 2021, 05:47:45 AM »
Thanks... I was just wondering, after a few days of droppings.

Did we reach freezing season maximum, then?

Freegrass

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Re: The 2021 melting season
« Reply #2 on: March 15, 2021, 06:05:54 AM »
It sure looks that way. The question is if the ice in Baffin bay will increase a lot, and if that can be offset by a loss of ice in the sea of Okhotsk, Bering, and maybe the Greenland sea.

But that's just me using visual tools. Oren will check the numbers later today to confirm.

For sure in a few days from now, when that storm hits the Atlantic side of the CAB, we'll see a big drop. It's not a good start of the season when a storm hits the most worrying part of the ASI...
« Last Edit: March 15, 2021, 06:18:41 AM by Freegrass »
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Aluminium

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Re: The 2021 melting season
« Reply #3 on: March 15, 2021, 07:21:19 AM »
March 6-14.

2020.

Stephan

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Re: The 2021 melting season
« Reply #4 on: March 15, 2021, 07:49:09 AM »
I evaluated the JAXA data of all freezing seasons from March 13 14 to the individual maximum to find out how often an increase of 0.21 M km² has happened after March 1314. This is the value needed to be higher than the actual maximum from March 10 (14.24 M km²). I grouped these evaluations into the different decades. The evaluation has three outcomes:
A - an increase higher than 0.22 M km² has happened in x years (Pass), which means the maximum has not been reached
B - an increase of 0.21 ± 0.01 M km² has happened in y years (Intermediate), which means the maximum may have been reached, but maybe not
C - an increase of less than 0.20 M km² has happened in z years (Fail), which means the maximum has already been reached and we can start the melting season thread.

                     A       B      C
1979-1989:    1       0     10
1990-1999:    1       1       8
2000-2009:    1       0       9
2010-2020:    0       1     10
sum:              3       2     37

Summary: It is highly likely that we can declare March 10, 2021 as the date of this year's JAXA extent maximum.
« Last Edit: March 15, 2021, 01:15:59 PM by Stephan »
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Pavel

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Re: The 2021 melting season
« Reply #5 on: March 15, 2021, 08:22:08 AM »
A new cyclone is coming from the Atlantic side. It has the GAC power of the bottom pressure of 962 hPa currently forecasted. The ice in the Atlantic side is relatively thin and we'll see how much damage it will get

oren

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Re: The 2021 melting season
« Reply #6 on: March 15, 2021, 09:51:41 AM »
Following three days of extent losses, concentrated in "real" seas such as Bering, Barents and the Greenland Sea, rather than the marginally attached Okhotsk, and considering the relatively late date, we are now officially switching over to the 2021 melting season. Fasten your seat belts!

SimonF92

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Re: The 2021 melting season
« Reply #7 on: March 15, 2021, 12:27:28 PM »
For anyone wanting a quick peek at the situation
Bunch of small python Arctic Apps:
https://github.com/SimonF92/Arctic

Freegrass

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Re: The 2021 melting season
« Reply #8 on: March 15, 2021, 01:55:41 PM »
Latest Five Day Forecast
Wind @ Surface
Large GiF!

That's gonna hurt...
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Aluminium

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Re: The 2021 melting season
« Reply #9 on: March 15, 2021, 02:46:50 PM »
This event is much stronger than we see usually. It's forecasted 100+ km/h at surface, up to 175 km/h at 850 hPa (nullschool). Further forecast is not much better.

BornFromTheVoid

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Re: The 2021 melting season
« Reply #10 on: March 15, 2021, 03:10:15 PM »
The refreeze in 10 day intervals
(click to play)
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Aluminium

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Re: The 2021 melting season
« Reply #11 on: March 15, 2021, 05:00:33 PM »
I found something similar in the 2016/2017 freezing season. The result was impressive.


Freegrass

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Re: The 2021 melting season
« Reply #12 on: March 15, 2021, 06:08:19 PM »
Great find Aluminium! Scary too... I was gonna say that the ice in March is much thicker than it is in December, but it's actually not that much thicker at all. This year the ice on the Atlantic side is abnormally thin, so lets hope that this storm either weakens, or moves to another place in the coming days. If it hits as forecasted today, I will call an ice free pole at the end of the melting season already...

This is what they call being in the wrong place at the wrong time, so let's hope the extra thickness is enough for the ice to not completely disintegrate like it did in 2016...

It'll be another good lesson to learn...


« Last Edit: March 15, 2021, 06:47:26 PM by Freegrass »
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bbr2315

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Re: The 2021 melting season
« Reply #13 on: March 15, 2021, 08:00:22 PM »
It looks like the weak ice in the ATL front is a relic of the weak ice along the Siberian front last winter (19-20). I wonder if there is a multi-year cycle here, if so, weak ice in X region (in this case Siberian shoreline) could portend a weak front in Y region thereafter under ordinary conditions.

The 365-day animations provided in this thread show this to be the case re: the ATL front and its origination.


Jim Hunt

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Re: The 2021 melting season
« Reply #14 on: March 15, 2021, 08:10:36 PM »
I found something similar in the 2016/2017 freezing season.

Not forgetting what the UK Met Office originally referred to as "Storm Frank" at the very end of 2015:



Here's the NASA/NSIDC analysis of that cyclone:

https://doi.org/10.1175/MWR-D-16-0234.1

I rather doubt that the currently forecast cyclone will have such a large effect, but that forecast may of course change over the next few days!
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Re: The 2021 melting season
« Reply #15 on: March 15, 2021, 08:18:15 PM »
It has been changing with every forecast .. a few days ago the forecast storm was much worse .. forecast central pressure in the low 950's ; forecast now low 970's and further sorth .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 .. you gotta laugh .. :)

Jim Hunt

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Re: The 2021 melting season
« Reply #16 on: March 15, 2021, 09:21:07 PM »
It has been changing with every forecast..

It depends where and when you look of course, but the ECMWF forecast a minimum MSLP of 959 hPa in their 0Z model run:

https://GreatWhiteCon.info/2021/02/the-2021-maximum-arctic-sea-ice-extent/#Mar-15
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Paul

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Re: The 2021 melting season
« Reply #17 on: March 15, 2021, 09:42:02 PM »
I think there is a little bit too much being read into the low pressure system and it's possible impacts. You can't compare the sea ice right now to how the ice looked back in December in 2015 and 2016 espoecially the latter as SSTS will be lower now, the ice is thicker(although as pointed out it looks thinner than average) and there has been some below average cold hitting that area in the last few days so ice temperatures will be much lower than they were in 2016 especially so I don't expect anything too dramatic. Fram export however will be noteworthy and the first year ice may reach the pole perhaps, not unprecedented of course but noteworthy.

Freegrass

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Re: The 2021 melting season
« Reply #18 on: March 15, 2021, 10:11:48 PM »
Those are all valid points Paul. It'll be interesting to see how much of the ice will get broken up...

Maybe we'll also find out once and for all if HYCOM or CS2SMOS had it right about the thickness of the ice in front of the Fram strait. With a little bad luck it won't even matter anymore if a lot of it gets transported out of Fram...
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Pagophilus

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Re: The 2021 melting season
« Reply #19 on: March 16, 2021, 02:55:00 AM »
And Lo! From under its mantle of clouds and darkness, the Ice appears. 

Fram Strait.  Worldview.   Pushed a lot for contrast on Photoshop.

Are those wavy lines of ice just north Svalbard 'melting ribbons' ?
You may delay, but time will not.   Benjamin Franklin.

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Re: The 2021 melting season
« Reply #20 on: March 16, 2021, 04:25:05 AM »
It looks like the weak ice in the ATL front is a relic of the weak ice along the Siberian front last winter (19-20). I wonder if there is a multi-year cycle here, if so, weak ice in X region (in this case Siberian shoreline) could portend a weak front in Y region thereafter under ordinary conditions.

The 365-day animations provided in this thread show this to be the case re: the ATL front and its origination.


It seems like every year a different area is weaker if you can find a pattern that would be interesting.

El Cid

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Re: The 2021 melting season
« Reply #21 on: March 16, 2021, 08:37:31 AM »
It looks like the weak ice in the ATL front is a relic of the weak ice along the Siberian front last winter (19-20). I wonder if there is a multi-year cycle here, if so, weak ice in X region (in this case Siberian shoreline) could portend a weak front in Y region thereafter under ordinary conditions.

The 365-day animations provided in this thread show this to be the case re: the ATL front and its origination.


It seems like every year a different area is weaker if you can find a pattern that would be interesting.

Absolutely! I can't see that pattern but it may be there. Worth examining.

HapHazard

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Re: The 2021 melting season
« Reply #22 on: March 16, 2021, 10:14:59 AM »
Are those wavy lines of ice just north Svalbard 'melting ribbons' ?

IDK but it sure is purty  :)

(changed curves in PS, North is down)

[in this pic, the clouds are streaming lines going up/down, and the melting ice is "coming off" the bottom, in case anyone was confused]

« Last Edit: March 16, 2021, 09:36:04 PM by HapHazard »

Freegrass

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Re: The 2021 melting season
« Reply #23 on: March 16, 2021, 11:41:42 AM »
There's a 50km big floe moving up the Alaskan coast and closing in on Barrow. I presume that's thick MYI?

https://go.nasa.gov/3ljGwG1
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Jim Hunt

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Re: The 2021 melting season
« Reply #24 on: March 16, 2021, 11:49:56 AM »
Are those wavy lines of ice just north Svalbard 'melting ribbons' ?

That depends on which "wavy lines" you are referring to. The "pseudo-color" layers on Worldview can help distinguish between ice and clouds:

https://go.nasa.gov/2Nr9uXY
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Pagophilus

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Re: The 2021 melting season
« Reply #25 on: March 16, 2021, 01:44:38 PM »
Thanks for the replies.  The red arrows on the image point to the areas of wavy lines I was referring to.  These wavy lines are aligned in an up-down axis in this image. To me these look like melting ribbons, indicating that active melting is already happening in this area.  (I am not referring to the stronger pattern of left to right lines which I assume are clouds.)

Some early melting might be expected here with the W. Spitzbergen Current in this area.
« Last Edit: March 17, 2021, 03:03:25 PM by Pagophilus »
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Freegrass

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Re: The 2021 melting season
« Reply #26 on: March 16, 2021, 02:44:39 PM »
Establishing the provenance of individual floes or areas of drifting ice takes time. This quick method uses a high contrast time series of amsr2-uhh from oct10-dec31 for an overview of drift.
I was actually completely relying on the 365 day HYCOM model that I posted earlier.

Remember the flute playing mouse getting its ass sucked into the beaufort sea? I think that big floe is part of his ass. And thus some of the last remaining MYI...

If it turns out that this is indeed the case, then that would mean that the HYCOM model is actually pretty good and reliable.
« Last Edit: March 16, 2021, 03:19:47 PM by Freegrass »
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jdallen

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Re: The 2021 melting season
« Reply #27 on: March 16, 2021, 04:57:36 PM »
This event is much stronger than we see usually. It's forecasted 100+ km/h at surface, up to 175 km/h at 850 hPa (nullschool). Further forecast is not much better.
Now that's what I call a roaring start.

It probably won't affect area and extent numbers significantly, but I think may have a major pre-conditioning effect by disrupting the ice.
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F.Tnioli

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Re: The 2021 melting season
« Reply #28 on: March 16, 2021, 05:21:29 PM »
What's the state of Polar Vortex? Does it exist at this time as something we could even remotely call a "vortex"?
To everyone: before posting in a melting season topic, please be sure to know contents of this moderator's post: https://forum.arctic-sea-ice.net/index.php/topic,3017.msg261893.html#msg261893 . Thanks!

Freegrass

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Re: The 2021 melting season
« Reply #29 on: March 16, 2021, 05:30:53 PM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!

The storm forecast hasn't changed much...

The polar vortex at 10hPa seems to be splitting again. This is 5 days out.
https://classic.nullschool.net/#2021/03/21/0600Z/wind/isobaric/10hPa/overlay=temp/orthographic=-45.05,89.62,662
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nadir

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Re: The 2021 melting season
« Reply #30 on: March 16, 2021, 05:59:24 PM »
There's a 50km big floe moving up the Alaskan coast and closing in on Barrow. I presume that's thick MYI?

https://go.nasa.gov/3ljGwG1

Judging from the animations above, maybe it's not MYI as much as extremely ridged and compacted ice during the winter, resulting in a huge thick floe difficult to break. Or maybe it's both.

Aluminium

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Re: The 2021 melting season
« Reply #31 on: March 16, 2021, 10:03:09 PM »
The latest GFS forecasts 964 mb in 84-102 hours. There is always some thin ice in that place. I expect notable effect in extent/area.

Lord M Vader

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Re: The 2021 melting season
« Reply #32 on: March 16, 2021, 10:04:38 PM »
While HYCOM has its limitations, there seems to be some good and bad news for the upcoming melting season.

Let's start with the positive news: both ESS, Laptev and Chukchi looks healthier this year compated to last year. I do not expect an early opening up of these sections.

The bad news then. The Atlantic sector looks terrible weak. Under the Wright circumstances the ice front might reach very , every close to the pole. The other ominous thing is the lack of thick MYI along the coast from Grenland to CAA. In addition, the every strong high pressure in the first half of February pushed thicker icke closer to the Alaskan coast. While an early opening up is not likely that's our least problem. If the CAA sector gets warmer this summer it might destroy the ice there. And leave the Arctic virtually void of any thick ice at all. That would open up for 2022 to be a year of ice destruction.

All in all, I do not expect any record low this year. I think of 2021 as more of a prepper year for a possible onslaught during 2022.

Iain

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Re: The 2021 melting season
« Reply #33 on: March 17, 2021, 08:57:34 AM »
Agree the CAA is one to watch, the ice bridges between it and the CAB don't usually break until late September, but there is so little thick ice there to start with they could break sooner and enormous amounts of thick-ish ice would migrate Southward.

The September minimum is a long way off, we'll see.
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Freegrass

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Re: The 2021 melting season
« Reply #34 on: March 17, 2021, 03:12:19 PM »
Latest Five Day Forecast
Wind @ Surface
Large GiF!
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Stephan

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Re: The 2021 melting season
« Reply #35 on: March 18, 2021, 06:58:22 AM »
I evaluated the JAXA data of all freezing seasons from March 17 to find out how often an increase of 0.12 M km² has happened after March 17. This is the value needed to be higher than the actual maximum from March 10 (14.24 M km²). I grouped these evaluations into the different decades. The evaluation has three outcomes:
A - an increase higher than 0.13 M km² has happened in x years (Pass), which means the maximum has not been reached
B - an increase of 0.12 ± 0.01 M km² has happened in y years (Intermediate), which means the maximum may have been reached, but maybe not
C - an increase of less than 0.11 M km² has happened in z years (Fail), which means the maximum has already been reached and the start of the melting season thread was a right decision.

                     A       B      C
1979-1989:    1       0     10
1990-1999:    2       1       7
2000-2009:    0       0     10
2010-2020:    1       1       9
sum:              4       2     36

Summary: It is not certain that there will be no new 2021 JAXA extent maximum in the next days...
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Freegrass

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Re: The 2021 melting season
« Reply #36 on: March 18, 2021, 07:17:33 AM »
Summary: It is not certain that there will be no new 2021 JAXA extent maximum in the next days...
That storm will be wreaking havoc in the next 24 hours, and I think this will prevent a new maximum. But it will be a close call for sure...

« Last Edit: March 18, 2021, 07:24:56 AM by Freegrass »
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Re: The 2021 melting season
« Reply #37 on: March 18, 2021, 08:14:14 AM »
GFS predicts 969 mb in 42-48 hours. Nothing extraordinary now but it's still strong and long-lived.

Freegrass

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Re: The 2021 melting season
« Reply #38 on: March 18, 2021, 11:23:24 AM »
Looking at the HYCOM model prediction for the next few days, I see the Svalbard gap closing up, more ice in Baffin Bay, and ice growth in the Greenland, Bering, and Okhotsk seas.

A new maximum seems very possible... Will Barents save the day?
« Last Edit: March 18, 2021, 11:41:02 AM by Freegrass »
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Re: The 2021 melting season
« Reply #39 on: March 18, 2021, 02:27:20 PM »
Yes there seems to be a lot of ice being spread out which is increasing extent but its false extent as the quality of the ice is nil and it will be gone ..poof in no time during the early Summer

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Re: The 2021 melting season
« Reply #40 on: March 18, 2021, 03:51:21 PM »
GFS predicts 969 mb in 42-48 hours. Nothing extraordinary now but it's still strong and long-lived.
Updated Fram volume export graph.
     The storm's forecast position and close isobars in the Fram Strait suggest that it will increase Fram export.  Just moving the ice from one place to another would not cause much immediate change to the total Arctic Extent/Area/Volume stats, but would contribute to longer-term ASI loss by moving ice southward into a higher melt zone.  Unlike last year at this time, this year there is not a pile of thick ice near the Fram Strait vulnerable to export.  But also true that this year the Atlantic side overall is already weak so any erosion from the storm(s) would be a deduction from an already depleted account.
« Last Edit: March 18, 2021, 05:33:07 PM by Glen Koehler »

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Re: The 2021 melting season
« Reply #41 on: March 18, 2021, 05:16:33 PM »
Currently winds are more favorable for Fram import than export. Not for a long time though.

Freegrass

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Re: The 2021 melting season
« Reply #42 on: March 18, 2021, 05:23:24 PM »
Latest Five Day Forecast
Wind @ Surface
Large GiF!

Two storms in a row. Fram export should become significant for the first time this year...
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gerontocrat

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Re: The 2021 melting season
« Reply #43 on: March 18, 2021, 06:40:51 PM »
Unlike last year at this time, this year there is not a pile of thick ice near the Fram Strait vulnerable to export. 
And Cryosat still insists there is
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Re: The 2021 melting season
« Reply #44 on: March 19, 2021, 04:30:16 AM »
Unlike last year at this time, this year there is not a pile of thick ice near the Fram Strait vulnerable to export.   
And Cryosat still insists there is
too bad we dont have on the ice data to verify the cryosat algorithym. More validation is needed for this product. if you read more about the complextity of different types of ice and there discussion about needing more field work to validate the interpritation of signals I do not think you would be as confident about cryosat thickness data yet.

 For all the negative opinions of the US navy some deserved some not the US navy has had a continuous sub presence in the arctic for better than 50 years. it is also true that measuring ice thickness from below using Lidar in subs is currently the most accurate way to measure ice thickness. That should be enough to convince you. IMO the most convincing reason HYCOM is more accurate is submarine wakes are visible on the surface when ice thickness is below a certain threshold. The primary objective of those subs is to remain hidden. That makes knowing how thick the ice is mission critical. A large area as shown on CryoSat of 2.5 -3.5 m ice near the Fram strait which HYCOM shows as 1.75-0.75 m would be a major mistake for a mission critical military operation with a year round presence. On the other hand the algorithm for cryostat is still being developed. As in not complete. This project is much more complex than calibrating this absorbance at this wavelength equals this thickness. We know optics change substantially when among other things ice gets stacked up. Maybe their first guess when they thought they were measuring thickness they are actually measuring stacking angle or edge fragmentation or a million other things. We know the different ways of forming ice produce different responses. My understanding of the mosaic mission is researchers were surprised by thin ice on the way to the pole which was consistent with what HYCOM was showing but not PIOMAS. That surprise prompted an effort to seek an algorithm to use CryoSat data to predict thickness. You seem to ignore that until that effort is validated HYCOM is the standard to beat. I believe when CryoSat is fully validated it will look close to HYCOM with minor differences not the major ones we see today.
« Last Edit: March 19, 2021, 06:20:10 AM by interstitial »

Freegrass

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Re: The 2021 melting season
« Reply #45 on: March 19, 2021, 04:56:37 AM »
Unlike last year at this time, this year there is not a pile of thick ice near the Fram Strait vulnerable to export. 
And Cryosat still insists there is
too bad we dont have on the ice data to verify the cryosat algorithym. More validation is needed for this product. if you read more about the complextity of different types of ice and there discussion about needing more field work to validate the interpritation of signals I do not think you would be as confident about cryosat thickness data yet.
For all the negative opinions of the US navy some deserved some not the US navy has had a continous sub pressence in the arctic for better than 50 years. it is also true that measuring ice thickness from below using lidar in subs is currently the most accurate way to measure ice thickness. That should be enough to convince you.
IMO the most convincing reason hycom is more accurate is submarine wakes are visable on the surface when ice thickness is below a certain threshold. The primary objective of those subs is to remain hidden. That makes knowing how thick the ice is mission critical. A large area as shown on cryosat of 2.5 -3.5 m ice near the fram strait which Hycom shows as 1.75-0.75 m would be a major mistake for a mission critical military operation with a year round pressence.
On the other hand the algorythim for cryostat is still being devoloped. As in not complete. This project is much more complex than calibrating this absorbance at this wavelength equals this thickness. We know optics change substantially  when among other things ice gets stacked up. Maybe thier first guess when they thought they were measuring thickness they are actually measuring stacking angle or edge fragmentation or a million other things. We know the different ways of forming ice produce diffrent responses.
My understanding of the mosaic mission is researchers were suprised by thin ice on the way to the pole which was consistent with what hycom was showing but not piomass. That surprise prompted an effort to seek an algorithym to use cryosat data to predict thickness. You seem to ignore that until that effort is validated Hycom is the standard to beat. I believe when crysat is fully validated it will look close to hycom with minor differences not the major ones we see today.
We're gonna get our assess kicked by Oren if we discuss those things here... But I just wanna say this one thing... (sorry Oren!)

The entire atmosphere consists of water... How many km's of water vapor does this measurement have to go through before it reaches the clouds, the snow that falls out of those clouds, and then the snow on the ice, the ice, and the water with different densities under the ice?

I would trust a submarine over a sattelite any day of the year...
When factual science is in conflict with our beliefs, we cuddle up in our own delusional fantasy where everything starts making sense again...

interstitial

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Re: The 2021 melting season
« Reply #46 on: March 19, 2021, 06:10:35 AM »
 season
We're gonna get our assess kicked by Oren if we discuss those things here... But I just wanna say this one thing... (sorry Oren!)
yea I forgot more flexibility in the slower freezing season than the melting season.

Stephan

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Re: The 2021 melting season
« Reply #47 on: March 19, 2021, 07:16:56 AM »
Still not finally decided...

I evaluated the JAXA data of all freezing seasons from March 18 to find out how often an increase of 0.09 M km² has happened after March 18. This is the value needed to be higher than the actual maximum from March 10 (14.24 M km²). I grouped these evaluations into the different decades. The evaluation has three outcomes:
A - an increase higher than 0.10 M km² has happened in x years (Pass), which means the maximum has not been reached
B - an increase of 0.09 ± 0.01 M km² has happened in y years (Intermediate), which means the maximum may have been reached, but maybe not
C - an increase of less than 0.08 M km² has happened in z years (Fail), which means the maximum has already been reached and the start of the melting season thread was a right decision.

                     A       B      C
1979-1989:    1       0     10
1990-1999:    2       0       8
2000-2009:    0       0     10
2010-2020:    2       0       9
sum:              5       0     37

Summary: It is not certain that there will be no new 2021 JAXA extent maximum in the next days...
It is too late just to be concerned about Climate Change

oren

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Re: The 2021 melting season
« Reply #48 on: March 19, 2021, 10:00:28 AM »
Thank you Stephan.
Just to be clear, we will continue with the melting thread in any case, taking the embarrassment in stride if it happens.

Regarding Hycom:
A. I doubt submarine data is fed into the model, sporadically or regularly.
B. I don't share the optimism about it being the prime or standard model, I have strong doubts about it. However it is considered a valid model for the purposes of this thread.
C. This year is a good test for the differences between Hycom, Cryosat+SMOS and PIOMAS, hopefully we will learn something from observations.
D. Please put further discussions of model qualifications in the Hycom, PIOMAS or Cryosat threads. In this thread assume all three are equally valid.

nadir

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Re: The 2021 melting season
« Reply #49 on: March 19, 2021, 12:14:49 PM »
Oren, ironically that was ok decision for the freezing season (it is easier for Hycom to predict thickening by freezing than thinning by melting, plus Hycom does ok with ice drift; C2MOS is not available in Summer). For the Summer we are left with Piomas only.

But As long as wild claims are controlled in the mid of Summer when Hycom shows paper-thin ice where buoys show otherwise, it is ok anyway.