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Author Topic: Latest PIOMAS update (July 2020)  (Read 1194105 times)

Juan C. García

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Re: Latest PIOMAS update (December)
« Reply #1200 on: December 16, 2016, 05:01:44 AM »
What do you think? Will we end up with a new lowest December record?
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.

Pavel

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Re: Latest PIOMAS update (December)
« Reply #1201 on: December 16, 2016, 10:34:55 AM »
I guess the biggest sea ice loss is happening right now as the thick ice exits through the Fram Strait and replaced by 1-year ice that struggles to build volume due to higher temperatures. NSIDC's extent grows rapidly till the end of December, but in August it may dramatically plunge because of thin ice

S.Pansa

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Re: Latest PIOMAS update (December)
« Reply #1202 on: December 16, 2016, 11:09:06 AM »
Will we end up with a new lowest December record?

My uneducated guess: We will start 2017 at least 1.000 km³ below the previous lowest, 2012.

Reasons:
- Dec weather & temps up until now and the forcast for the upcoming week.

As others have noted this should lead to an enhanced Fram export.
And I suspect the FDD anomaly will increase even further, expecially compared to 2012.

Of course, going by my predictive capabilities, 2016 will come in way above 2012  :D (which would actually be good news)

Juan C. García

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Re: Latest PIOMAS update (December)
« Reply #1203 on: December 16, 2016, 02:15:44 PM »
I made a mistake choosing the maximum monthly melt for February. It is not 2011, it is 2013. Also, it didn't appear January on the posted image. Sorry for that. I include the corrected table.

I believe that with this table, it is possible to see the inertia of one month to the next, so it don't surprise me that there are records going on from June 2012 to February 2013 (until 2016 appeared on November).
On 2016, we have records on April and May, but June and July did not promote the huge melt of ice. Even though, 2016 continue to have huge melt on August and the high sea surface temperature on Oct-Dec, made that 2016 start to have new records now.
I surely expect to have a new record on December 2016 and in fact, I expect it could continue, at least until January 2017.
« Last Edit: December 16, 2016, 02:58:33 PM by Juan C. García »
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.

jai mitchell

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Re: Latest PIOMAS update (December)
« Reply #1204 on: December 17, 2016, 03:06:23 AM »
Wow JUAN

That is a fantastic reference chart.  Amazing how a matrix of numbers and colors can contain so much information.

to answer your question. 

I think that the Dec. avg will come in at 11,270 Km^3 and am guessing from your chart that would be around 45.8% below the 80-89 value.  but you tell me,

« Last Edit: December 17, 2016, 03:15:20 AM by jai mitchell »
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Neven

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Re: Latest PIOMAS update (December)
« Reply #1205 on: December 17, 2016, 10:54:05 AM »
A great chart indeed, but maybe you should change the colour scheme by removing the yellow.
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Jim Pettit

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Re: Latest PIOMAS update (December)
« Reply #1206 on: December 17, 2016, 02:54:52 PM »
I believe that with this table, it is possible to see the inertia of one month to the next, so it don't surprise me that there are records going on from June 2012 to February 2013 (until 2016 appeared on November).
On 2016, we have records on April and May, but June and July did not promote the huge melt of ice. Even though, 2016 continue to have huge melt on August and the high sea surface temperature on Oct-Dec, made that 2016 start to have new records now.
I surely expect to have a new record on December 2016 and in fact, I expect it could continue, at least until January 2017.

Nice chart, indeed.

I maintain a number of PIOMAS-based volume pages. Among them is a spreadsheet using much the same data as your chart, only pivoted, and with a different color code. Too, I use the first year of satellite data--1979--as a baseline. (Of interest on that spreadsheet: November 2016 is the only November on the record that showed a loss of more than 60% of November 1979's number--obviously an ominous sign.)

FWIW, I maintain a couple of graphs based on those same data. These first two are identical, the only difference being that one is drawn on a polar chart, while the other isn't:





I also have an interactive, animated 3D graph showing the same numbers:



In fact, this last one, if rotated so the "camera" is directly overhead, shows results somewhat similar to your nifty chart:


Juan C. García

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Re: Latest PIOMAS update (December)
« Reply #1207 on: December 17, 2016, 04:49:29 PM »
Thanks Jai, Neven and Jim for your comments.
In this chart, I am looking to balance the idea of weather and climate.
NSIDC uses a climate definition based on the average of 1981-2010. On the other hand, Piomas makes normally two comparisons: a) against 1979 and b) against the average of 1979 to the last full year (1979-2015 on this November).
I don't really like any of these methods.
The Piomas comparison against 1979 could be criticized to be against just one year, that its, 1979 alone cannot be use as "climate", it is just a year and a year with maximums on the whole months. I believe that 1979 represents the ASI that we could have on the 60's and 70's, even could be a low value for those decades, but I not willing to try to prove it and I am also not willing to accept the critics that it is not climate, it is just one year.
On the other hand, I find also unacceptable the NSIDC 1981-2010 and the Piomas 1979-2015. The ASI has been going down on this period. So, if someone use the average as "climate", it is really lowering the ASI values in which they are comparing to.
So, having a lack of "stable" ASI values, I find fair to compare de decades against the first decade of values that we have (1980-89), using this decade as climate and looking to prove that the ASI has been changing, decade by decade, thinking that these changes represent the real effect of climate change, that we are having on the ASI.
It is kind of method that IJIS uses in their graphs and it is the method that I like most.

PS: I will look to change the colors on the graph. Maybe the colors that Jim uses in his last graph are a good choice.
« Last Edit: December 17, 2016, 05:48:49 PM by Juan C. García »
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.

Nightvid Cole

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Re: Latest PIOMAS update (December)
« Reply #1208 on: December 18, 2016, 06:15:14 PM »
What do you think? Will we end up with a new lowest December record?

Yes, given that the volume on December 1st was at a record low by a significant margin and the anomalous warmth has continued.

Juan C. García

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Re: Latest PIOMAS update (December)
« Reply #1209 on: December 20, 2016, 10:47:23 PM »
This is new graph, with new colors.
If someone wants to play with the numbers or colors of the graph, you can find the Excel file on:

https://www.dropbox.com/s/nnh5j3kstqcmzzo/Piomas%20ASI%20Lost%20vs%201980-89.xlsx?dl=0

Changing the colors is easy, because they are with conditional format. Just choose the table values (C5:O24) and change the format rules.
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.

Juan C. García

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Re: Latest PIOMAS update (December)
« Reply #1210 on: December 20, 2016, 11:19:22 PM »
For those who want to have the comparisons against an average on a bigger time frame, it is easy to change it. Just change the row with the comparison average.
This is the image against the 1979-2000 average. The colors change automatically.
The file is in:

https://www.dropbox.com/s/xl5aot9irgoreiy/Piomas%20ASI%20Lost%20vs%201979-2000.xlsx?dl=0

(If you want to make it public, you also have to change the row titles)
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.

Siffy

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Re: Latest PIOMAS update (December)
« Reply #1211 on: January 01, 2017, 11:08:14 PM »
When can we expect the next set of PIOMAS data any way?

jai mitchell

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Re: Latest PIOMAS update (December)
« Reply #1212 on: January 03, 2017, 07:59:40 PM »
When can we expect the next set of PIOMAS data any way?


in a few days,
 :'(
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Wipneus

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Re: Latest PIOMAS update (January)
« Reply #1213 on: January 04, 2017, 07:38:00 AM »
I think it may be any time now. GIOMAS, the global variant, has just updated.

Just selecting the NH data we can have a preview for what PIOMAS will bring.

 

Neven

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Re: Latest PIOMAS update (January)
« Reply #1214 on: January 04, 2017, 10:11:15 AM »
I'm going to say what I said last month: Oh, Jesus...

BTW, those colours look perfect now, Juan.
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TerryM

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Re: Latest PIOMAS update (January)
« Reply #1215 on: January 04, 2017, 10:34:30 AM »
This is so much worse than anything I had ever imagined that I'm at a loss for words.


Terry


be cause

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Re: Latest PIOMAS update (January)
« Reply #1216 on: January 04, 2017, 10:51:16 AM »
I'm suprised at how much ice is being claimed .. b c
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

A-Team

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Re: Latest PIOMAS update (January)
« Reply #1217 on: January 04, 2017, 01:36:23 PM »
Quote
so much worse than anything I had ever imagined...
surprised at how much ice is being claimed
An 8.1% drop relative to the previous low in 2012 would be significant. If the rest of this winter is record warmth like 2015, the ice will be quite vulnerable in melt season regardless of cloud and melt pond conditions.

The thickest ice seems to be in an implausible position relative to Tschudi ice age in the 1990-2016 animation, notably the older ice is on the outside, rather than inside, of the very thickest Piomas ice.  And the whole map is in near-total contradiction with many months of Hycom ice thickness, which is a conventional half-dome declining out from the CAA.

We've wondered before if the Piomas algorithm works all that well for thinner ice. Right now though, SMOS only kicks in for thicknesses below 0.5 m so the SMOS + Cryosat combination product is needed. However that does not seem available quite yet for the date of interest.

Analysis of the warmest Arctic winter, 2015–2016
RI Cullather, YK Lim, LN Boisvert, L Brucker, JN Lee, SMJ Nowicki
Geophysical Research Letters 43 (20) 2016

The Impact of the Extreme Winter 2015/16 Arctic Cyclone on the Barents–Kara Seas
LN Boisvert, AA Petty, JC Stroeve
Monthly Weather Review 144 (11), 4279-4287 2016

Journal of Geophysical Research: Atmospheres 121 (19)   2   2016
Melt onset over Arctic sea ice controlled by atmospheric moisture transport
J Mortin, G Svensson, RG Graversen, ML Kapsch, JC Stroeve, ...
Geophysical Research Letters 2016

The Arctic is becoming warmer and wetter as revealed by the Atmospheric Infrared Sounder
LN Boisvert, JC Stroeve
Geophysical Research Letters 42 (11), 4439-4446

https://www.climate.gov/news-features/understanding-climate/noaas-2016-arctic-report-card-visual-highlights
« Last Edit: January 04, 2017, 02:04:28 PM by A-Team »

jdallen

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Re: Latest PIOMAS update (January)
« Reply #1218 on: January 04, 2017, 10:08:29 PM »
Quote
so much worse than anything I had ever imagined...
surprised at how much ice is being claimed
An 8.1% drop relative to the previous low in 2012 would be significant. If the rest of this winter is record warmth like 2015, the ice will be quite vulnerable in melt season regardless of cloud and melt pond conditions.
<snip>
It will be quite vulnerable regardless. 

Unless there is a massive swing to much colder temperatures, there is no way the current deficit can be corrected.  The damage has already been done.  There is not enough time for colder temperatures to thicken the ice where it has already formed and needs to go (past 2 Meters).  The warmth has prevented hardening of the ice to make it more resistant to mechanical forces.

There isn't enough time.
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FishOutofWater

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Re: Latest PIOMAS update (January)
« Reply #1219 on: January 04, 2017, 10:13:41 PM »
To make matters worse warm water from the Atlantic has been driven faster into the Arctic seas by the intense storms that have moved from the Greenland sea to the Barents and Kara seas. The heat content of the water in the Barents sea is way above normal so ice that is pushed towards the Barents will melt from below.

Neven's "melting momentum" is already rolling in January.

jdallen

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Re: Latest PIOMAS update (January)
« Reply #1220 on: January 04, 2017, 10:34:04 PM »
To make matters worse warm water from the Atlantic has been driven faster into the Arctic seas by the intense storms that have moved from the Greenland sea to the Barents and Kara seas. The heat content of the water in the Barents sea is way above normal so ice that is pushed towards the Barents will melt from below.

Neven's "melting momentum" is already rolling in January.

We saw that last winter; warmer Atlantic water gets driven up around the islands before dropping down into the deeper basin.  A-Team has done a number of great animations that demonstrate it.  The whole front from Greenland to Severna Zemlya has turned into a battleground between the ice and incoming "warm" Atlantic water.  That contest hasn't stopped since its inception in late 2015.
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jai mitchell

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Re: Latest PIOMAS update (January)
« Reply #1221 on: January 04, 2017, 10:51:47 PM »
To make matters worse warm water from the Atlantic has been driven faster into the Arctic seas by the intense storms that have moved from the Greenland sea to the Barents and Kara seas. The heat content of the water in the Barents sea is way above normal so ice that is pushed towards the Barents will melt from below.

Neven's "melting momentum" is already rolling in January.

to make matters much worse, there is every reason to believe that the effect that we have been seeing linking tropical mid and upper tropospheric tropical heat and water vapor into the arctic via Pacific and Atlantic pathways will only increase as the NH spring starts to increase ITCZ expansion northward. (pic from 2 days ago --> causing record warm temperatures in Barrow AK.

----------
P.S. note to Wip.  The value of 9.5 on the front page of this thread for the Dec avg. . .my brain is not allowing me to believe it. . .please, please PLEASE correct the value to what the actual estimation is. . . (please)

I surmise that if this is the correct value that we will find a creative effort by the good people at UW to check and 'correct' their methodology/sensor error/impact of snow cover. . .what ever it takes to bring it up to at least 10.75. . .

« Last Edit: January 04, 2017, 11:08:31 PM by jai mitchell »
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Tigertown

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Re: Latest PIOMAS update (January)
« Reply #1222 on: January 05, 2017, 12:59:17 AM »
I thought 9.5 was the actual value for the beginning of Dec. 2016, not the Dec. average. Maybe I am looking in the wrong place.

A-Team

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Re: Latest PIOMAS update (January)
« Reply #1223 on: January 05, 2017, 03:34:01 PM »
Quote
JD: The whole front from Greenland to Severna Zemlya has turned into a battleground between the ice and incoming "warm" Atlantic water.
Both portals to the Arctic Ocean continue to experience deteriorating conditions in early 2017. In the Svalbard area, the departure of the ice boundary from bathymetry is becoming significant, to the point that the epic N-ICE2015 study (to 83ºN) would scarcely be possible to repeat this year.

Prior to Nansen's extraordinary expedition of 1893–96, the 'Gulf Stream' was thought to continue into the central Arctic Ocean, restricting sea ice to the coastal periphery. However the remnant meridional current (West Spitzbergen) aka Atlantic Waters is observed today in recent years to instead follow the continental shelf boundaries north and eastward some 300 m below the surface for reasons given in the 1930's by Rossby.

One important anomaly to monitor may thus be the distance open water is observed poleward of the continental shelf in the vicinity of Svalbard (though this is complicated by the Yermak Plateau and Sofia Deep).

With the advent of daily SMOS thin ice, a more nuanced partition between open water, thin ice and thick ice can improve significantly on the old water vs ice tracking model, which seems to grossly understater the current problem (final frame shows <0.5 m ice almost to 85ºN).

On 03 Jan 17, open water is seen well poleward of the 3000 m isobath, per SMOS, Sentinel-1AB and AMSR2. This is not strictly indicative of straying current warmth as warm moist advected air, downwelling infrared, poleward winds and long-fetch waves all have a role to play as well.

The Chukchi not only has open water on this late date (yellow) near the Bering Strait on 03 Jan 17, despite a few days of nominal freeze-over earlier, but the overall region is showing far less solid ice (green: >90% concentration) than previously.
« Last Edit: January 05, 2017, 04:01:50 PM by A-Team »

Jim Williams

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Re: Latest PIOMAS update (January)
« Reply #1224 on: January 05, 2017, 04:15:58 PM »
One important anomaly to monitor may thus be the distance open water is observed poleward of the continental shelf in the vicinity of Svalbard (though this is complicated by the Yermak Plateau and Sofia Deep).

So are you saying that previously the Atlantic surface current was simply falling into deep water at  Svalbard and now some of it seems to be remaining at the surface northward of the deep water line?

A-Team

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Re: Latest PIOMAS update (January)
« Reply #1225 on: January 05, 2017, 05:55:08 PM »
As discussed earlier, AW is found at a depth appropriate to its relative buoyancy, with density determined by salinity and temperature, in comparison to fresher Arctic Ocean water. AW brings in enough heat every few years to melt the entire ice pack; however it exits with some of that heat and much of what's left remains at lower layers subject to gradual heat and salinity diffusion.

AW is now considerably warmer than it has been historically (ie gradients are stronger) and retreat of the ice in the Svalbard - FJI - SZ area may have increased mixing in the water column by various mechanisms, with some of its heat now having direct and indirect implications for local surface ice formation and retention.

While there are several hundred published papers on the oceanography of this region, the 'current' state of affairs in this critical region is probably best explored in the special journal issue for N-ICE2015 which would make for an important new forum were it not mostly paywalled or still in review two years after the expedition began. Or rather, the forum could be exploring what has changed just in the last two years here.

http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-9291/specialsection/NICE1/

Otherwise, this region is rather an outlier in terms of area coverage for surface temperature products, significant wave height and so forth, often with contradictory, ambiguous, artifactual or implausible displays. SMOS and AMSR2, along with the odd buoy, are probably the best resources for us at this time while we await expert assimilation of near-daily Sentinel-1AB overpasses into other favored products. (The resolution is such that just a line of pixels from Greenland to the Siberian is something like 200 forums wide, challenging to make desktop time series at these file sizes.)
« Last Edit: January 05, 2017, 06:15:54 PM by A-Team »

RoxTheGeologist

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Re: Latest PIOMAS update (January)
« Reply #1226 on: January 05, 2017, 06:25:18 PM »

AW is now considerably warmer than it has been historically (ie gradients are stronger) and retreat of the ice in the Svalbard - FJI - SZ area may have increased mixing in the water column by various mechanisms, with some of its heat now having direct and indirect implications for local surface ice formation and retention.


That's a really very interesting observation. I have though for a while that a mechanism that will reduce ice coverage is related to the AW. It's a feedback mechanism that includes less dense (warmer) AW; More briny surface water (lower concentrations of younger more briny ice melt); Increased swell size and more storms. All will reduce the stratification in the Arctic Ocean. As the surface lens of fresher water covering the CAB becomes shallower, more briny, and smaller, less ice will form, further reducing stratification. What A-Team has shown is happening at Svalbard is likely to be the model by which the whole of the CAB will become ice free, areas of the Arctic where previously AW would be covered by 100s of meters of stratified fresher and colder water are now being effectively mixed. Peripheral seas, with the input of freshwater from rivers, are likely to have ice coverage for longer.

meddoc

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Re: Latest PIOMAS update (January)
« Reply #1227 on: January 05, 2017, 08:40:17 PM »
So, it's gonna be around 13, 800 km3.
Let this sluggish growth continue & we' re in for global catastrophe this Year already.

Pmt111500

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Re: Latest PIOMAS update (January)
« Reply #1228 on: January 06, 2017, 07:50:53 AM »

AW is now considerably warmer than it has been historically (ie gradients are stronger) and retreat of the ice in the Svalbard - FJI - SZ area may have increased mixing in the water column by various mechanisms, with some of its heat now having direct and indirect implications for local surface ice formation and retention.


That's a really very interesting observation. I have though for a while that a mechanism that will reduce ice coverage is related to the AW. It's a feedback mechanism that includes less dense (warmer) AW; More briny surface water (lower concentrations of younger more briny ice melt); Increased swell size and more storms. All will reduce the stratification in the Arctic Ocean. As the surface lens of fresher water covering the CAB becomes shallower, more briny, and smaller, less ice will form, further reducing stratification. What A-Team has shown is happening at Svalbard is likely to be the model by which the whole of the CAB will become ice free, areas of the Arctic where previously AW would be covered by 100s of meters of stratified fresher and colder water are now being effectively mixed. Peripheral seas, with the input of freshwater from rivers, are likely to have ice coverage for longer.

Nice explanation of the mechanism that I think would keep the North Atlantic Drift flowing at least during the Arctic night. During summers though the Gulf Stream (and associated currents would likely struggle againts fresh water inflow frim Siberian rivers and GIS. (aww, the amount of types when wroting on phone....)
Cooling the outside by heat pump.

Jim Williams

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Re: Latest PIOMAS update (January)
« Reply #1229 on: January 06, 2017, 04:49:19 PM »
Nice explanation of the mechanism that I think would keep the North Atlantic Drift flowing at least during the Arctic night. During summers though the Gulf Stream (and associated currents would likely struggle againts fresh water inflow frim Siberian rivers and GIS. (aww, the amount of types when wroting on phone....)

I think the tropics are going to keep pushing the water, at least for now.  Where it streams is the big question.

Pmt111500

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Re: Latest PIOMAS update (January)
« Reply #1230 on: January 06, 2017, 05:05:30 PM »

I think the tropics are going to keep pushing the water, at least for now.  Where it streams is the big question.

Yep, no doubt tropics will be warmer than Arctic even on equable climate, be the difference 15 or 5°C, this means there's heat still flowing from tropics by gravity alone. Of the same opinion about the big question. Wish there were some models that would allow fixing the locations of ocean currents just so they'd give indication of the types of weather they generate.
Cooling the outside by heat pump.

Jim Williams

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Re: Latest PIOMAS update (January)
« Reply #1231 on: January 06, 2017, 05:13:31 PM »

I think the tropics are going to keep pushing the water, at least for now.  Where it streams is the big question.

Yep, no doubt tropics will be warmer than Arctic even on equable climate, be the difference 15 or 5°C, this means there's heat still flowing from tropics by gravity alone. Of the same opinion about the big question. Wish there were some models that would allow fixing the locations of ocean currents just so they'd give indication of the types of weather they generate.

All I know on that is that the Western Boundary Currents have trended more poleward.  I keep looking and the Gulf Stream and Greenland and pondering that fact.

jai mitchell

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Re: Latest PIOMAS update (January)
« Reply #1232 on: January 06, 2017, 07:29:47 PM »
Just look at that WV pouring in over Chukchi Peninsula!
 :o

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Re: Latest PIOMAS update (January)
« Reply #1233 on: January 07, 2017, 11:30:58 PM »
The PIOMAS numbers for December are out.As expected (feared?), last month finished with 13,078 km3, a substantial (8433, or >6%) drop from 2012's previous lowest 12/31 reading of 12,195 13,921 km3.

More startlingly, 2016 finished 2,574 km3, or 16.4%, lower than it began. This chart shows that drop well:



Yowza.

I went ahead and updated my other primary PIOMAS graphics, as well.

These first two illustrate that last month's average daily volume was for the first time more than 50% lower than the average volume measured in the same month in 1979:





These last three are my standard 3d volume graphs; click to animate/rotate/zoom:






« Last Edit: January 08, 2017, 01:33:16 PM by Jim Pettit »

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Re: Latest PIOMAS update (January)
« Reply #1234 on: January 08, 2017, 12:15:52 AM »
Thanks for your valuable visualizations Jim...

But...

"13,078km^3" does not seem like a "substantial drop" from "2012's previous lowest 12,195 km^3".

Maybe transposed, or a wrong digit in there?

TIA for the corrected number.

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Re: Latest PIOMAS update (January)
« Reply #1235 on: January 08, 2017, 12:17:59 AM »
@Jim Pettit      Is that the daily value at the end of Dec. 2016 compared to the monthly average for Dec. 2012? I am confused. It looks like the daily value and I read that the volume for Dec. 2016 was 11,200 km3, which I would think would be the average. Hoping it was just a typo and can  straighten out in my mind.

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Re: Latest PIOMAS update (January)
« Reply #1236 on: January 08, 2017, 12:37:45 AM »
2012 day 365 is 13.921

Quote
2012 365  13.921

13.078 is 2016 day 365

Only .843 k km3 seems a small differential when at day 335 it was at 9.511 vs 10.235 a diff of .724

(GIOMAS graph had appeared to suggest about 1.2 k km3 difference.)

jai mitchell

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Re: Latest PIOMAS update (January)
« Reply #1237 on: January 08, 2017, 02:12:54 AM »
@Jim Pettit      Is that the daily value at the end of Dec. 2016 compared to the monthly average for Dec. 2012? I am confused. It looks like the daily value and I read that the volume for Dec. 2016 was 11,200 km3, which I would think would be the average. Hoping it was just a typo and can  straighten out in my mind.

I am actually a little surprised if this is true, when I did my estimate, I figured it would cool off a bit more than it did mid-month.

I think that the Dec. avg will come in at 11,270 Km^3
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Re: Latest PIOMAS update (January)
« Reply #1238 on: January 08, 2017, 03:13:35 AM »
That was a good estimate, as 13,078 km3 was the daily value for the last day of 2016 and 11,200 km3 was the December average.

http://psc.apl.uw.edu/research/projects/arctic-sea-ice-volume-anomaly/

"December 2016 sea ice  volume was 11,200 km3 , nearly  1000 km3 below the previous record for December in 2012.   This record is in part the result of anomalously high temperatures throughout the Arctic for November and end of December discussed here   and here.  2016 December  volume was 52% below the maximum December ice volume in 1979,  39% below the 1979-2015 mean, and about 1.3 standard deviations below  the long term trend line."

Jim Pettit

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Re: Latest PIOMAS update (January)
« Reply #1239 on: January 08, 2017, 03:16:53 AM »
Thanks for your valuable visualizations Jim...

But...

"13,078km^3" does not seem like a "substantial drop" from "2012's previous lowest 12,195 km^3".

Maybe transposed, or a wrong digit in there?

TIA for the corrected number.

Yes, a simple error; trying to finish up  too many items at once, and I inadvertently put a monthly average in, My apologies. I'm away from my computer at the moment--I'm writing this on my iPad--but will have it correct in the morning. But to clarify: I'm noting that the month-end/year-end volume measurement for 2016 is substantially lower than the same number for 2012, the previous record low.

NOTE: fixed. Please see the revised comment in question.
« Last Edit: January 08, 2017, 01:34:55 PM by Jim Pettit »

Juan C. García

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Re: Latest PIOMAS update (January)
« Reply #1240 on: January 08, 2017, 06:52:50 AM »
This is the table with 1979 as the baseline. Of course, the percentage of Arctic Sea Ice Volume (ASIV) lost is the biggest on this baseline.

Some interesting points, with the 1979 baseline:
  • There are four months on which 2016 is the lowest on record: April, May, November and December.
  • December 2016 is the first December in which we have lost more than half of the ASIV.
  • 2016 has become the second year lowest on record, with 46.4% ASIV lost. The first one is still 2012, with 46.7% ASIV lost (whole year average).
On September loses:
  • 2012 is the lowest on record, with more than ¾ (77.6%) of ASIV lost. The second is 2011 with 73.5% and the third is 2016 with 73.2%.
  • The 2010-16 ASIV lost is striking:  69.7%. If we round the number (as PIOMAS usually does) we have 70% ASIV lost! And it can increase when we have the full decade (2010-19).
  • For NSIDC, the second year with September lowest on record is 2007. But the PIOMAS figures tell another story. 2007 is the seventh lowest on record. The first six lowest years on record are: 2012, 2011, 2016, 2010, 2013 and 2015.
PD: We should also be concern about the 2010-16 July to November average: 61.7% ASIV lost (not shown on the graph). From my point of view, this can mean that when we will have an ice-free Arctic, it could happen on more than one month.
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)
« Reply #1241 on: January 08, 2017, 09:04:35 AM »
I updated my graphics, see the top post

Daily gridded thickness data was not updated yet (monthly was), I will wait for that before posting the maps.

Attaching the anomaly graph.

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Re: Latest PIOMAS update (January)
« Reply #1242 on: January 08, 2017, 10:00:10 AM »
And here, we see Wipneus write the Arctic's epitaph in graphic form.

Does anyone else note, that between this time and the start of the active melt season, 2016's anomaly over the 1979-2009 baseline actually increased?

I'll be watching for that.
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Re: Latest PIOMAS update (January)
« Reply #1243 on: January 08, 2017, 10:55:40 AM »
Based on these figures we are starting 2017 with approximately 20% less ice than 2012.  That  suggests we have a lot of catching up to do to to  recover to  2012 levels.
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Re: Latest PIOMAS update (January)
« Reply #1244 on: January 08, 2017, 11:56:52 AM »
Based on these figures we are starting 2017 with approximately 20% less ice than 2012.  That  suggests we have a lot of catching up to do to to  recover to  2012 levels.

Yeah, and we haven't touched on the issue of integrity yet.
I guess these satellite data also tend to err upon the least side of drama.
Small ponds, cracks, polynyas, etc.  won't show up in the measurements.

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Re: Latest PIOMAS update (January)
« Reply #1245 on: January 08, 2017, 01:48:22 PM »
Quote
these Piomas daily gridded data also tend to err upon the least side of drama.
Small ponds, cracks, polynyas, etc. won't show up in the measurements.
Right. It appears from 2013 grid cell discussions between Wipneus and Chris that the resolution of the computed thickness is 120x360 = 43,200 spreadsheet cells, which would be the same as map graphical size in pixels before rescaling. I've attached a colored rectangle below of those dimensions.

These numbers are consistent with the extremely crude coastline rendering (which will pixelate, not get better, upon enlargement) seen on the best daily thickness maps that can be produced. For example, look at the Bering Strait and Ellesmere Island outlines from the Nov 16 daily animation in #1152.

If you now take the area of the Arctic Ocean proper and divide by the number of pixels representing it, this gives pixel size in square km (except that they may be including considerable area beyond the Arctic Ocean).

So if a single pixel has to represent a 40 km x 40 km block down on the ice, a lot of detail like ridges, leads, polynyas, low concentration ice, age-related albedo and features of even the largest floes falls through the cracks.

It is already computationally expensive to make the daily grid and to increase that say to 10 km x 10 km might bump that time sixteen-fold. But doing that could greatly exceed precision in some of the inputs and capabilities of the algorithm.

Piomas has by far the worst resolution of any product we use here, not because the scientists behind it are dumb or lazy but because wide area accurate ice thickness maps are inherently very hard to produce.

http://psc.apl.washington.edu/zhang/IDAO/data_piomas.html inputs into the model
http://tinyurl.com/jgub5uo wipneus and chris going on in 2013

Here is a single data line from Wip's site: replace each space with a tab to load into a spreadsheet. The data is given to 10 significant digits in places whereas quoted error suggests 2 at best. The units were not indicated but could be millimeters.

4955.4986 4625.0463 4331.5092 4103.9947 3824.106975 3608.2857 3454.496475 3247.6158 3046.0212 2904.382 2765.08795 2628.7281 2495.42325 2417.323875 2340.4976 2214.355 2090.54755 2019.64525 1949.8992 1881.613725 1814.44275 1748.8151 1684.120425  ...
« Last Edit: January 08, 2017, 06:29:23 PM by A-Team »

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Re: Latest PIOMAS update (January)
« Reply #1246 on: January 08, 2017, 02:43:59 PM »
Has someone tracked why the remaining thick ice dislocated so far out, if PIOMAS is to believed, that looks like most of it will enter Fram next summer. Not that it matters a lot, forecasting is always easier afterwards...
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Re: Latest PIOMAS update (January)
« Reply #1247 on: January 08, 2017, 03:34:05 PM »
Based on these figures we are starting 2017 with approximately 20% less ice than 2012.  That  suggests we have a lot of catching up to do to to  recover to  2012 levels.

Can you please explain how a drop of 12,195km3 (Dec 2012) to 11,200km3 (Dec 2016) results in 20% less ice? It doesn't in any type of mathematics that I know.

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Re: Latest PIOMAS update (January)
« Reply #1248 on: January 08, 2017, 03:41:12 PM »
Based on these figures we are starting 2017 with approximately 20% less ice than 2012.  That  suggests we have a lot of catching up to do to to  recover to  2012 levels.

Can you please explain how a drop of 12,195km3 (Dec 2012) to 11,200km3 (Dec 2016) results in 20% less ice? It doesn't in any type of mathematics that I know.
It's closer to 12 percent. That number (20%) evidently came from mistakenly combining a daily value with an average which made the difference seem larger.

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Re: Latest PIOMAS update (January)
« Reply #1249 on: January 08, 2017, 04:36:12 PM »
Has someone tracked why the remaining thick ice dislocated so far out, if PIOMAS is to believed, that looks like most of it will enter Fram next summer. Not that it matters a lot, forecasting is always easier afterwards...

i think that less mechanical resistance due to thin ice with low integrity could play a role here. after all, whenever the winds and currents blow (or try to blow) ice around, it matters whether the space it is blown to is ice free, 5 meters thick or one solid ice sheet as compared to millions of small junks that are only held together by thin first year ice. just a thought, others may have more insight.