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Author Topic: HYCOM  (Read 6884 times)

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Re: HYCOM
« Reply #100 on: August 06, 2020, 07:52:13 PM »
The university of Hamburg appears to be a sea ice concentration product. Unlike Masie 1km and 4km area products.

oren

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Re: HYCOM
« Reply #101 on: August 07, 2020, 03:09:44 AM »
Thanks, interstitial. I am familiar with MASIE but just didn't understand that was what you were referring to. MASIE is less used on the forum because it is not recommended for comparison between years (being based on a manual algorithm), however it is perfectly suitable for making predictions for the current melting season. Note however that MASIE is only about extent, not area, as far as I am aware.

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Re: HYCOM
« Reply #102 on: August 07, 2020, 06:09:20 AM »
It helped me understand what data was out there. Generally I assume you know about this stuff. Masie does not distinguish between area and extent. If their is ice they count it if not the don't (an approximation of their words not mine). To me that sounds like a description of area though their philosophy on the subject is rather nebulous to me.

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Re: HYCOM
« Reply #103 on: August 13, 2020, 05:50:18 PM »
To my eyes Hycom is predicting significant losses in Greenland, Beufort and Chukchi seas. As always full screen is best to see the details.

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Re: HYCOM
« Reply #104 on: August 13, 2020, 06:03:03 PM »
Once again on thickness charts the forecast will always show at least white until it has completely melted out on nowcast.
Concentration charts clear up when it goes to zero. All of the blue and some of the blue green is below the 15% concentration threshold of most products.

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Re: HYCOM
« Reply #105 on: August 13, 2020, 06:06:10 PM »
The CAA seems to be more resilient than I expected but could flush out.

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Re: HYCOM
« Reply #106 on: August 17, 2020, 03:11:02 AM »
Looking at piomas model I see ice thinning by 1 m between 4/15 and 7/15. In less central locations the ice thins 1.25 m while in more central locations the ice thins by 0.75m. That is a melt rate of 8mm to 14mm per day. I also looked at Hycom on the same dates and came up with similar numbers. 7/15 includes about 4 weeks after the solstice. We are now almost three weeks beyond that. We are getting close to the time when the CAB normally starts to refreeze. The Beaufort will probably melt to the end.
Thanks for your interesting post interstitial. A few notes:
* The CAB continues to accumulate volume until May 5th-10th, at least according to PIOMAS.
* Peak volume loss rate is between mid-June and end-July. Using Wipneus regional numbers, an area of ~4M km2 loses ~4000 km3, so about 1m over 6 weeks, roughly 2.5 cm/day. Of course this mixes up top melt, bottom melt and export/import.

According to this interesting article referenced by A-Team on the Mosaic thread:

Quote
On our transects – regular walks across the floe ... We recorded a gradual decrease in the average ice thickness: a drop of approximately one metre over the course of July.

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...ablation stakes allow us to distinguish between the melting below and melting above. ... We measured an average of ~85cm of ice thinning across our stakes sites from 26 June to 30 July. Surface ablation accounted for seventy-five percent of that thinning, while bottom melting made up the remaining twenty-five percent.

Quote
The remotely operated underwater vehicle (ROV) “Beast” surveys the ice from below ... Comparing the maps produced over several dives showed that not all the ice melted at the same speed. Especially the deep keels that extended more than 8 metres into the comparably “warm” ocean were eroding quickly. In some parts of the ridged ice, keel depth decreased by up to 2 metres in just the first 14 days.

This was in the very southern CAB so fits more or less with the average PIOMAS loss calculated above for the whole CAB.

vox_mundi

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Re: HYCOM
« Reply #107 on: November 15, 2020, 03:48:32 PM »
It seems the Navy Lab has discontinued ice concentration updates of HYCOM since the middle of October-Nov 1. Any story to this? Or has the administration ordered an end to all this science stuff?
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Re: HYCOM
« Reply #108 on: November 15, 2020, 07:25:04 PM »
It seems the Navy Lab has discontinued ice concentration updates of HYCOM

 I see what you mean re the archive, but the "nowcast" still seems to be updating:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

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Re: HYCOM
« Reply #109 on: November 15, 2020, 09:29:30 PM »
Do you have a link to that, because here is what I'm using (I'm looking for ice thickness, sorry) and it stops at Nov 2, 2020

https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticictn_nowcast_anim30d.gif

Kinda coincidence that it stopped on election day.
« Last Edit: November 15, 2020, 09:40:08 PM by vox_mundi »
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

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Re: HYCOM
« Reply #110 on: November 15, 2020, 10:26:30 PM »
Do you have a link to that, because here is what I'm using (I'm looking for ice thickness, sorry) and it stops at Nov 2, 2020

https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticictn_nowcast_anim30d.gif

Kinda coincidence that it stopped on election day.
Try https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticice_nowcast_anim30d.gif

which is a link from the box at the bottom of https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/arctic.html

WHOOPS - but the ice thickness animation does stop at 2nd November. damn
« Last Edit: November 15, 2020, 10:34:24 PM by gerontocrat »
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vox_mundi

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Re: HYCOM
« Reply #111 on: November 15, 2020, 11:15:08 PM »
Spooky; huh?  ???
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

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Re: HYCOM
« Reply #112 on: November 19, 2020, 02:52:07 AM »
And now it works!
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gerontocrat

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Re: HYCOM
« Reply #113 on: November 19, 2020, 11:23:34 AM »
And now it works!
Conspiracy theory

- the US navy won't update the thickness maps until they've processed the latest thickness data from the sonar records of the subs playing cat and mouse with the Russian subs under the Arctic.
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