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Author Topic: Latest PIOMAS update (September)  (Read 785502 times)

Wipneus

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Re: Latest PIOMAS update (November update)
« Reply #2200 on: November 03, 2017, 07:25:36 PM »
Gridded thickness data has updated, the "official" volume data not yet.

Late here, I will post some stuff now, rest tomorrow.

Here is the October animation.

Wipneus

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Re: Latest PIOMAS update (November update)
« Reply #2201 on: November 03, 2017, 07:47:52 PM »
Daily volume and volume anomaly graphs. PIOMAS volume is 4th lowest now after being 5th earlier this month.

The Google site software gives me problems today, so no uploading to the site today (same for other daily updated data and graphs as well).


Wipneus

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Re: Latest PIOMAS update (November update)
« Reply #2202 on: November 03, 2017, 07:52:21 PM »
Life is coming back with respect to Fram export.

Pavel

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Re: Latest PIOMAS update (November update)
« Reply #2203 on: November 03, 2017, 09:18:45 PM »
Thanks for the update, very appreciated.
Quote
Life is coming back with respect to Fram export
Due to the current synoptic conditions the Fram export increases rapidly. It looks like the thickest CAB ice is prone to leave the basin by summer

Blizzard92

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Re: Latest PIOMAS update (November update)
« Reply #2204 on: November 04, 2017, 05:22:32 PM »
My October PIOMAS plots are available at http://sites.uci.edu/zlabe/arctic-sea-ice-volumethickness/.
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Shared Humanity

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Re: Latest PIOMAS update (November update)
« Reply #2205 on: November 04, 2017, 06:55:10 PM »

jai mitchell

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Re: Latest PIOMAS update (November update)
« Reply #2206 on: November 06, 2017, 03:47:59 PM »
Univ of Calgary Study indicates that Cryosat-2 has overestimated thickiness of first-year sea ice by as much as 25% due to salinity content of upper layers.

Overall this bias of extra thckness indicates an overestimate of up to 17 percent of total volume in recent years.

https://www.ucalgary.ca/utoday/issue/2017-10-24/arctic-sea-ice-may-be-thinning-faster-scientists-initially-predicted#.WgBdozOXxfA.twitter

Quote
“It has been assumed by the scientific community that CryoSat-2 can accurately measure the sea ice freeboard, which is the ice we can see above sea level,” says Nandan. “But that ice is covered in snow and the snow is salty close to where the sea ice surface is. The problem is, microwave measurements from satellites don’t penetrate the salty snow very well, so the satellite is not measuring the proper sea ice freeboard and the satellite readings overestimate the thickness of the ice.”
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Shared Humanity

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Re: Latest PIOMAS update (November update)
« Reply #2207 on: November 06, 2017, 04:29:20 PM »
Yikes!

Forest Dweller

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Re: Latest PIOMAS update (November update)
« Reply #2208 on: November 06, 2017, 04:59:13 PM »
Yeah so the salinity is affecting readings for the thin ice particularly, from 11%-25% it seems.
Overall % though?
At which point in the year, or what year altogether is one referring to in such a case i wonder?
Seems clear that such an overestimate would become more and more the larger the area of thin ice becomes.
Perhaps it would be useful to have some corrected variations on the measurements visualized as well accounting for the time frame/amount of thin ice.

I.E. if 25% of the ice is at 1-2 feet thickness, 25% is at 2-3 feet thickness...then half of all the ice is overestimated at average 17-18% for a given time or period.
Total ice thickness over estimation would therefore be half of that again so around 8.5 to 9%.
Make sense?
« Last Edit: November 06, 2017, 05:25:15 PM by Forest Dweller »

Niall Dollard

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Re: Latest PIOMAS update (November update)
« Reply #2209 on: November 06, 2017, 09:11:09 PM »
Univ of Calgary Study indicates that Cryosat-2 has overestimated thickiness of first-year sea ice by as much as 25% due to salinity content of upper layers.

Beginning to feel like groundhog day.

I can count at least 5 separate times this study has been raised in different threads in the past 3 weeks or so !

Freezing thread #241 & later #257
PIOMAS v Cryosat #287

In this thread (Latest PIOMAS update thread) it was raised at #2193 which sparked the most interest to date.

 

Wipneus

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Re: Latest PIOMAS update (November mid monthly update)
« Reply #2210 on: November 19, 2017, 06:27:18 PM »
Mid monthly update of PIOMAS gridded thickness data is in: 1-15 November.

Attached is the animation.

Wipneus

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Re: Latest PIOMAS update (November mid monthly update)
« Reply #2211 on: November 19, 2017, 06:30:25 PM »
Volume calculated from thickness data, Nov 1-15:

array([ 7.73,  7.79,  7.85,  7.94,  8.05,  8.16,  8.25,  8.32,  8.4 ,
        8.53,  8.67,  8.8 ,  8.94,  9.07,  9.18])

Attached are the voluem and anomaly graphs.



Wipneus

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Re: Latest PIOMAS update (November mid monthly update)
« Reply #2212 on: November 19, 2017, 06:41:01 PM »
The regional volume data was uploaded as:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

Attached the update of the calculated Fram volume export.

Neven

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Re: Latest PIOMAS update (November mid monthly update)
« Reply #2213 on: November 19, 2017, 08:06:46 PM »
Thanks, Wipneus! Very useful.

So, 2017 is still on a par with 2010, chugging along into the long night.
Compare, compare, compare

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Re: Latest PIOMAS update (November mid monthly update)
« Reply #2214 on: November 19, 2017, 10:14:26 PM »
Here is November sea ice thickness from RASM-ESRL, including ten days of forecast. Again, we don't know how this was initialized back in mid-August nor how to compare it numerically to Piomas but do have some idea how the RASM-ESRL model adds thickness to existing ice and how it freezes open water (which is rapidly shrinking in the Chukchi and even pushing into the Barents towards the end, much more so than on the same date in 2016).
« Last Edit: November 19, 2017, 10:51:33 PM by A-Team »

Wipneus

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Re: Latest PIOMAS update (December update)
« Reply #2215 on: December 06, 2017, 10:00:40 AM »
PIOMAS has updated, both the official volume data as the gridded thickness data.

Attached the anomaly graph, 2017 volume takes the third lowest place after 2016 and 2012.

Wipneus

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Re: Latest PIOMAS update (December update)
« Reply #2216 on: December 06, 2017, 10:08:01 AM »
Here is the animation of November 2017.

Wipneus

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Re: Latest PIOMAS update (December update)
« Reply #2217 on: December 06, 2017, 10:37:24 AM »
Thickness map for 30 November 2017, compared with previous years.

Neven

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Re: Latest PIOMAS update (December update)
« Reply #2218 on: December 06, 2017, 10:47:15 AM »
Thanks, Wipneus. I'll be posting a PIOMAS update on the ASIB tonight.
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Wipneus

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Re: Latest PIOMAS update (December update)
« Reply #2219 on: December 06, 2017, 11:12:48 AM »
Daily Fram volume export.

Wipneus

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Re: Latest PIOMAS update (December update)
« Reply #2221 on: December 06, 2017, 02:52:38 PM »
Thickness map for 30 November 2017, compared with previous years.
I'm intrigued by the 'thickest ever' November ice on the north shores of the New Siberian Islands.  I suspect this is due to the Beaufort Gyre operating freely, piling up the ice like it has never done before.
Arctic ice is healthy for children and other living things.

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Re: Latest PIOMAS update (December update)
« Reply #2222 on: December 06, 2017, 03:06:41 PM »
Here is the three-way thickness comparison for 30 Nov 2017: Piomas, Mercator Ocean, NOAA-ESRL.

Pavel

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Re: Latest PIOMAS update (December update)
« Reply #2223 on: December 06, 2017, 03:38:15 PM »
Some strong ice has formed along the Siberian coast. I think it will drift outward of the coast later. Also the thick MYI drifts to the Beaufort sea, at least some of it should survive next melt season. In general the Inner Basin already has got plenty of strong ice so that I'm confident no disaster should happen next year

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Re: Latest PIOMAS update (December update)
« Reply #2224 on: December 06, 2017, 09:13:00 PM »
My PIOMAS maps have been updated for November 2017 at http://sites.uci.edu/zlabe/arctic-sea-ice-volumethickness/
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Re: Latest PIOMAS update (December update)
« Reply #2225 on: December 06, 2017, 09:37:46 PM »
Quote
thick MYI drifts to the Beaufort sea ... Inner Basin already has got plenty of strong ice so that I'm confident no disaster
You might be less confident of that if you had actually looked at the anomaly data (says the exact opposite) or considered what November tells us about the ice thickening rate in Dec, Jan, Feb, Mar, Apr (nothing), melt ponds in May (less than nothing) and summer clouds and wind (less than less than nothing).

Neven

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Re: Latest PIOMAS update (December update)
« Reply #2226 on: December 07, 2017, 12:29:04 AM »
PIOMAS update is up on the ASIB.
Compare, compare, compare

Jim Hunt

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Re: Latest PIOMAS update (December update)
« Reply #2227 on: December 07, 2017, 03:43:32 PM »
What's more my own humble musings on the festive season in the Arctic have also been published recently:

"The 2017/18 Festive Season in the Arctic"
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Wipneus

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Re: Latest PIOMAS update (Mid December update)
« Reply #2228 on: December 20, 2017, 08:52:35 AM »
The mid-monthly (1-15 Dec) update of PIOMAS gridded sea ice thickness is here.

Calculated volume on the 15th is 12.6 [1000 km3], third lowest after 2016 and 2012.

The animation is attached.

Wipneus

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Re: Latest PIOMAS update (Mid December update)
« Reply #2229 on: December 20, 2017, 10:09:51 AM »
Volume and volume anomaly graphs.

Wipneus

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Re: Latest PIOMAS update (Mid December update)
« Reply #2230 on: December 20, 2017, 10:13:30 AM »
Some thicker ice can be seen moving thru the Fram Strait. This is what it means for the volume export.

Neven

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Re: Latest PIOMAS update (Mid December update)
« Reply #2231 on: December 20, 2017, 01:27:01 PM »
Volume and volume anomaly graphs.

Gap with 2012 closes some more. Thanks, Wip.
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oren

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Re: Latest PIOMAS update (Mid December update)
« Reply #2232 on: December 20, 2017, 03:35:00 PM »
Interestingly, the main volume in the CAB is drifting "westwards", which gives hope that the thick ice could be more protected from export this year.

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Re: Latest PIOMAS update (December update)
« Reply #2233 on: December 20, 2017, 05:56:32 PM »

"The 2017/18 Festive Season in the Arctic"
Why does 2015/16 suddenly stop in January on the Area and Extent graphs?

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Re: Latest PIOMAS update (Mid December update)
« Reply #2234 on: December 20, 2017, 10:35:08 PM »
Interestingly, the main volume in the CAB is drifting "westwards", which gives hope that the thick ice could be more protected from export this year.

But next year killed in the Beaufort and Chukchi?
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Re: Latest PIOMAS update (December update)
« Reply #2235 on: December 21, 2017, 04:30:37 PM »
Why does 2015/16 suddenly stop in January on the Area and Extent graphs?

Are you thinking of 2012/13? Whilst they eventually covered the 2012 minimum, unfortunately the University of Hamburg haven't done their AMSR2 sums for October through December of 2012 as yet.
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Wipneus

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Re: Latest PIOMAS update (January update)
« Reply #2236 on: January 05, 2018, 08:54:29 AM »
PIOMAS has updated, both the official volume data and the gridded thickness data are available.
Latest value ( 2017-12-31) is  14.418 [1000 km3], third lowest for the day after 2016 and 2016.

Attached the volume and volume anomaly graphs, click for larger sizes.

Wipneus

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Re: Latest PIOMAS update (January update)
« Reply #2237 on: January 05, 2018, 08:58:43 AM »
The thickness animation for the last month.

It seems you need to click, even with size less than 700x700, for the animation to start.

Neven

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Re: Latest PIOMAS update (January update)
« Reply #2238 on: January 05, 2018, 09:28:22 AM »
Thanks, Wip. In the meantime, Stefan Hendricks reports from the observations front:

Quote
Jan 2018 update with Dec 2017 Arctic #seaice thickness. Continued slow ice growth with lowest observed Oct-Dec volume gain so far.

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Wipneus

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Re: Latest PIOMAS update (January update)
« Reply #2239 on: January 05, 2018, 11:17:17 AM »
The thickness map on 31-12-2017 compared with recent years.

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Re: Latest PIOMAS update (January update)
« Reply #2240 on: January 05, 2018, 01:15:14 PM »
shocking to see how much volume disappeared in some areas in recent years

A-Team

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Re: Latest PIOMAS update (January update)
« Reply #2241 on: January 05, 2018, 02:26:01 PM »
Quote
It seems you need to click, even with size less than 700x700
It sometimes helps to save, crop off one column of pixels from an edge, optionally do a gif-differencing, then re-save and re-load to forum. Though today nothing seems to help. It is uploading all the gif frames today rather than only the first as it sometimes does.

Here is the matching Ascat for the same 32 days. Click to view. Piomas does fairly well on Fram export but isn't effectively displaying the action over at the narrower Nares Strait.

Note the ice being exported out the Fram is a merge of two ice streams, one originating from the Laptev and the other thick coastal CAA ice. (Textbook depictions invariably show ice moving out from the Chukchi along a 'Transarctic Drift' but 20 years of sea ice age animations and buoy tracking do not.)
« Last Edit: January 05, 2018, 02:40:17 PM by A-Team »

Wipneus

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Re: Latest PIOMAS update (January update)
« Reply #2242 on: January 05, 2018, 06:01:18 PM »
Update of the Fram volume export graph. Some thick ice exiting is pushing up the number in the second half of December. Note that average export in December is about 0.25 [1000km3 /month]

Lord M Vader

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Re: Latest PIOMAS update (January update)
« Reply #2243 on: January 05, 2018, 06:25:23 PM »
Wipneus: It seems like the map with thickness differences for the years 2007-2017 are calculated for November 30. Should be December 31 I presume...

Happy New Ice Year between :) Was a while since I was here now....

//LMV

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Re: Latest PIOMAS update (January update)
« Reply #2244 on: January 05, 2018, 06:34:09 PM »
My PIOMAS graphics have been updated through December 2017. They are available at http://sites.uci.edu/zlabe/arctic-sea-ice-figures/ and http://sites.uci.edu/zlabe/arctic-sea-ice-volumethickness/.
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Lord M Vader

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Re: Latest PIOMAS update (January update)
« Reply #2245 on: January 05, 2018, 06:42:55 PM »
Great, thanks Zack!

A little bit surprising that the Laptev Sea ice is thicker than normal. Deformated sea ice or just due to cold conditions?

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Re: Latest PIOMAS update (January update)
« Reply #2246 on: January 05, 2018, 10:20:07 PM »
Piomas Volume Lost, versus 1979-2000 average.
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.

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Re: Latest PIOMAS update (January update)
« Reply #2247 on: January 05, 2018, 10:39:17 PM »
Piomas Volume Lost, versus 1981-2010 average.

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.

Neven

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Re: Latest PIOMAS update (January update)
« Reply #2248 on: January 05, 2018, 10:48:58 PM »
I've posted the latest PIOMAS update on the ASIB, including stuff about CryoSat and the situation wrt temps and snow cover: PIOMAS January 2018.
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Re: Latest PIOMAS update (January update)
« Reply #2249 on: January 05, 2018, 11:21:55 PM »
Effect of Snow Salinity on CryoSat-2 Arctic First-Year Sea Ice Freeboard Measurements
V Nandan et al 17 October 2017 DOI: 10.1002/2017GL074506

Sea ice thickness retrievals at the CryoSat-2 frequency require accurate measurements of sea ice freeboard from the main radar scattering horizon is at the snow/sea ice interface.

Using an extensive snow thermo-physical dataset from [measured] late winter conditions in the Canadian Arctic, we examine the role of saline snow on first-year sea ice on the location of radar scattering, its ability to decrease radar penetration depth, and its impact of exaggerating FYI thickness estimates.

Based on the dielectric properties of saline snow commonly found on FYI the vertical shift in scattering is ~7 cm. A thickness-dependent snow salinity correction factor for FYI freeboard estimates significantly reduces CryoSat-2 FYI retrieval error.

Relative error reductions of ~11% are found for an ice thickness of 0.95 m and ~25% for 0.7 m. Our method also helps to close the uncertainty gap between SMOS and CryoSat-2 thin ice thickness retrievals. Our results indicate that snow salinity should be considered for FYI freeboard estimates.

During the formation of seasonal first-year sea ice (FYI), a small amount of brine is expelled upward, resulting in a thin brine layer on the ice surface. With subsequent snow accumulation, there is an upward wicking of brine into the snow cover. This wicking produces brine-wetted snow, primarily within the bottom 6–8 cm, which have salinities ranging from 1 to 20 parts per thousand.  The brine within the snow alters the dielectric and microwave scattering properties of the snow leading to significantly reduced radar penetration.

With the recent and rapid decline of MYI, and its replacement by FYI, the role of snow salinity should be considered whenever FYI freeboard is estimated using CryoSat-2 on local to pan-Arctic scales. [paraphrased selections]
« Last Edit: January 05, 2018, 11:35:53 PM by A-Team »