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Author Topic: Latest PIOMAS update (July mid-monthly update)  (Read 754949 times)

Wipneus

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2350 on: May 21, 2018, 04:59:57 PM »
PIOMAS gridded thickness data has updated, last day 15 May. Volume calculated from thickness is now 4th place behind 2017, 2016 and 2011.

Attached is the animation 1-15 May.

Wipneus

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2351 on: May 21, 2018, 06:41:42 PM »
Updated Fram volume export graph: it seem import is a better name.

New is the grey line in the background which indicates the 1979-2017 monthly average.  2018 is well behind.

Wipneus

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2352 on: May 21, 2018, 06:46:16 PM »
Updated daily volume and volume-anomaly graphs.

miki

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2353 on: May 21, 2018, 06:54:57 PM »
Thanks, Wipneus, as always.

Neven

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2354 on: May 21, 2018, 07:41:16 PM »
Thanks, Wip! Highly surprising news!  :)
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jdallen

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2355 on: May 21, 2018, 08:51:29 PM »
Thanks, Wip! Highly surprising news!  :)
Highly surprising indeed considering the weather and extent changes!

Now, to make sense of it...
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magnamentis

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2356 on: May 22, 2018, 12:37:55 AM »
almost each time i get more convinced that those numbers are flawed by a factor that will soon be unveiled once they show thick ice where's open water.  a bit exagerated perhaps but something of that kind.

the basics LxWxH ad looking at the two-dimensional values and then at winter temps, freezing days and so non it's almost impossible that they're correct.

the most interesting part IMO is that the part in the algorithm that's flawed either once was not significant or did not matter while with the recent chages of the ice conditions there must be something that's spoiling the results under certain circumstances and ever more often.

i'm sure that others see this different, i'm just curious what future will bring us in reference to
sea-ice-volume calculations.
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jdallen

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2357 on: May 22, 2018, 02:35:42 AM »
almost each time i get more convinced that those numbers are flawed by a factor that will soon be unveiled once they show thick ice where's open water.  a bit exagerated perhaps but something of that kind.

the basics LxWxH ad looking at the two-dimensional values and then at winter temps, freezing days and so non it's almost impossible that they're correct.
I'm pretty skeptical as well, but we'll see what shakes out.
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bbr2314

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2358 on: May 22, 2018, 02:49:44 AM »
almost each time i get more convinced that those numbers are flawed by a factor that will soon be unveiled once they show thick ice where's open water.  a bit exagerated perhaps but something of that kind.

the basics LxWxH ad looking at the two-dimensional values and then at winter temps, freezing days and so non it's almost impossible that they're correct.

the most interesting part IMO is that the part in the algorithm that's flawed either once was not significant or did not matter while with the recent chages of the ice conditions there must be something that's spoiling the results under certain circumstances and ever more often.

i'm sure that others see this different, i'm just curious what future will bring us in reference to
sea-ice-volume calculations.
If snowcover on land can inflate the cryosphere by 4,600KM^3 in April, perhaps the contribution to the sea ice in mid-May is even larger? This could make for a "false" excess in volume that melts wayyyy faster than normal, = the drop in May / June that often presents in the graphs ^?

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2359 on: May 22, 2018, 06:16:06 AM »
I believe the 3 meter thick ice north of Laptev modeled by PIOMAS is far thinner. Any guesses as to why? Remaining fragments of thick MYI  frozen in a thinner sheet causing ULS and/or CryoSat to overestimate due to lack of necessary resolution?
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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2360 on: May 22, 2018, 09:06:34 AM »
I too was surprised by the low drop in volume but I can see why I rather than PIOMAS may have been mislead. While my focus has been on the warmth in Central Arctic (as displayed by the DMI graph) and Barents (where the most dramatic changes are happening), it's actually been fairly cold in many regions including CAA, Hudson, Baffin, Kara and Laptev.

Additionally, the lack of Fram Strait export is likely a contributing factor.

Neven

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2361 on: May 22, 2018, 10:06:38 AM »
I too was surprised by the low drop in volume but I can see why I rather than PIOMAS may have been mislead. While my focus has been on the warmth in Central Arctic (as displayed by the DMI graph) and Barents (where the most dramatic changes are happening), it's actually been fairly cold in many regions including CAA, Hudson, Baffin, Kara and Laptev.

Additionally, the lack of Fram Strait export is likely a contributing factor.

Yes, these are probably the reasons.
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bbr2314

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2362 on: May 22, 2018, 05:14:42 PM »
I too was surprised by the low drop in volume but I can see why I rather than PIOMAS may have been mislead. While my focus has been on the warmth in Central Arctic (as displayed by the DMI graph) and Barents (where the most dramatic changes are happening), it's actually been fairly cold in many regions including CAA, Hudson, Baffin, Kara and Laptev.

Additionally, the lack of Fram Strait export is likely a contributing factor.
Fram Strait isn't exporting because the ice is mostly melting out before it can be exported (IMO)

FishOutofWater

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2363 on: May 22, 2018, 05:50:43 PM »
It has been cold where ice will melt out later. That means there's going to be a steep drop in thickness unless the weather turns cool and cloudy.

magnamentis

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2364 on: May 22, 2018, 08:28:03 PM »
If snowcover on land can inflate the cryosphere by 4,600KM^3 in April, perhaps the contribution to the sea ice in mid-May is even larger? This could make for a "false" excess in volume that melts wayyyy faster than normal, = the drop in May / June that often presents in the graphs ^?

even though i'm not that deep into snow-cover topic like you are (less privy with it) i had a similar idea, i.e. how much of that ice thickness is snow? but as i said, dunno enough to speak out about that, i'm really curious and of course, as always, it's possible that i'm simply wrong in my assumption, often facts are not logical for the ignorant (me in this case) at first glance, hence let's see ;)
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magnamentis

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2365 on: May 22, 2018, 08:31:37 PM »
It has been cold where ice will melt out later. That means there's going to be a steep drop in thickness unless the weather turns cool and cloudy.

that's what i thought last year and it did not happen but perhaps this year is different.

i find it very interesting that many are not comfy with data that were considered reliable over many years. that is my main question if i'm not totally off:

which of the recent changes in sea-ice conditions (or snow cover) is responsible for an "eventual" flaw in the algorithm ( if there is such a flaw which i believe but don't insist)
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Ken Feldman

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2366 on: May 22, 2018, 10:15:19 PM »
I believe the 3 meter thick ice north of Laptev modeled by PIOMAS is far thinner. Any guesses as to why? Remaining fragments of thick MYI  frozen in a thinner sheet causing ULS and/or CryoSat to overestimate due to lack of necessary resolution?

Ridging and rafting during the refreeze season can cause ice to grow much thicker than the 2 meters or so it would get just from the cold weather.

See this website for more information about how sea ice forms:  https://nsidc.org/cryosphere/seaice/characteristics/formation.html

Here's an excerpt that explains ridging and rafting:

Quote
If the ocean is rough, the frazil crystals accumulate into slushy circular disks, called pancakes or pancake ice, because of their shape. A signature feature of pancake ice is raised edges or ridges on the perimeter, caused by the pancakes bumping into each other from the ocean waves. If the motion is strong enough, rafting occurs. If the ice is thick enough, ridging occurs, where the sea ice bends or fractures and piles on top of itself, forming lines of ridges on the surface. Each ridge has a corresponding structure, called a keel, that forms on the underside of the ice. Particularly in the Arctic, ridges up to 20 meters (60 feet) thick can form when thick ice deforms. Eventually, the pancakes cement together and consolidate into a coherent ice sheet. Unlike the congelation process, sheet ice formed from consolidated pancakes has a rough bottom surface.

Wipneus

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2367 on: May 26, 2018, 03:08:45 PM »
PIOMAS has upgraded (upto 22 May) the gice ice category data set. For a refresher see my explanation laste month here.

I attach the gice graph for this  month (22nd May), and for comparison the one for last month (22nd April) as well.

What can be observed is that the area covered by ice thicker than 1.46m hardly changes between the two months. The area covered by thinner ice gets a lot smaller (your average ice cover thickens!).

In June we expect to see the category 1.46-2.61m drop as well.

oren

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2368 on: May 26, 2018, 03:44:20 PM »
Thank you Wipneus. Some points of interest about the chart:
This year has the highest level of >0.71m ice in the past decade, which gives some hope of a higher minimum area in Sept.
2016 clearly stood out as the worst in the thinner ice categories at this date, while 2017 was the worst in the thicker ice categories.
Finally, looking at all the graphs, and at the Sept 10th area, I think it's clear that 2012 was not a fluke at all as some consider. 2016 came very close to it in September, and the May situation seems to steadily deteriotate in all categories, meaning that the coming years have a greater chance of producing another "fluke".

numerobis

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2369 on: May 26, 2018, 07:07:18 PM »
I believe the 3 meter thick ice north of Laptev modeled by PIOMAS is far thinner. Any guesses as to why? Remaining fragments of thick MYI  frozen in a thinner sheet causing ULS and/or CryoSat to overestimate due to lack of necessary resolution?

Ridging and rafting during the refreeze season can cause ice to grow much thicker than the 2 meters or so it would get just from the cold weather.

Flaherty's Nanook of the North has some nice footage of this phenomenon. He was filming near Inukjuak. It was clearly more than just a couple meters then!

TenneyNaumer

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2370 on: May 27, 2018, 08:11:17 AM »
Re: PIOMAS

The high volume for 2009 and 2015 are nearly the same on the graph.

Doesn't stand to reason.

Further, ice in 2009 was fundamentally different from the slush of 2015. 

And...  the average temperature of the ice has to be much higher than it was 9 years ago. 

There is something way off in their algorithm and has been for years.

But I repeat myself.

crandles

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2371 on: May 27, 2018, 12:26:08 PM »
Re: PIOMAS

The high volume for 2009 and 2015 are nearly the same on the graph.

Doesn't stand to reason.

How are you ruling out slow rate of decline now the MYI is down to minimal levels (and FYI replaces itself each winter) and some natural variability?

[Or does this sound like cognitive dissonance: I was expecting a crash and it hasn't happened but I don't want to change my views and admit the rapid Arctic ice free sceptics were right.]

TenneyNaumer

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2372 on: May 30, 2018, 05:04:00 AM »
Re: PIOMAS

The high volume for 2009 and 2015 are nearly the same on the graph.

Doesn't stand to reason.

How are you ruling out slow rate of decline now the MYI is down to minimal levels (and FYI replaces itself each winter) and some natural variability?

[Or does this sound like cognitive dissonance: I was expecting a crash and it hasn't happened but I don't want to change my views and admit the rapid Arctic ice free sceptics were right.]

I am not taking your point, crandles.  I have been saying for many years that PIOMAS cannot be right, that the increases in volume from the low must be due to problems with the algorithms.  Of course, there might have been some increase due to natural variation, but the consistent increase over several years cannot have been right, IMO. Tell me how the water-logged slush can be measured in the same way that a similar section of tightly compressed multi-year ice can?  Further, slushy ice cannot be same temperature.  And, there is the stuff that resembles swiss cheese.  How is that being handled?

oren

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2373 on: May 30, 2018, 07:51:41 AM »
I have been saying for many years that PIOMAS cannot be right, that the increases in volume from the low must be due to problems with the algorithms.  Of course, there might have been some increase due to natural variation, but the consistent increase over several years cannot have been right, IMO. Tell me how the water-logged slush can be measured in the same way that a similar section of tightly compressed multi-year ice can?  Further, slushy ice cannot be same temperature.  And, there is the stuff that resembles swiss cheese.  How is that being handled?
No reason to think why natural variation cannot explain it. Even in a strong downtrend prolonged upturns are possible and probable when volatility is high, which is certainly the case for arctic sea ice volume.
Remember, PIOMAS is not a measurement, but a model. There are possible errors in its calibration as the arctic is nowadays composed mainly of FYI while it used to be composed of mainly MYI, but I think overall its results mostly show agreement with measurements, and also agree with common sense.

TenneyNaumer

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2374 on: May 30, 2018, 08:29:03 PM »
I do not agree that common sense would tell us that sea ice volume would go consistently up for 5 straight years when we know that the temperatures in the Arctic have also been going up.  Is it also common sense that PIOMAS shows the sea ice increasing over the past few months?  In any case, by the end of this summer, I think we'll have some answers.

http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.1.png

crandles

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2375 on: May 31, 2018, 12:30:13 AM »
I do not agree that common sense would tell us that sea ice volume would go consistently up for 5 straight years when we know that the temperatures in the Arctic have also been going up.  Is it also common sense that PIOMAS shows the sea ice increasing over the past few months?  In any case, by the end of this summer, I think we'll have some answers.

http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.1.png




Looking for 5 years of consistent gains. May 2011 to May 2015 looks like it does so and I don't see many if any other occurences.

If the trend is flat, which I agree I don't think it is, the chances of this happening is 1 in 16. Given the number of potential start points in above graph (about 33*12 = 396) so should happen about 25 times if trends were flat and changes not correlated. Occurring ~once instead of 25 times is not a sign of upward trend but of downward trends and a bit of natural variability.

Peter Ellis

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2376 on: May 31, 2018, 11:41:40 AM »
I do not agree that common sense would tell us that sea ice volume would go consistently up for 5 straight years

http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.1.png




Looking for 5 years of consistent gains. May 2011 to May 2015 looks like it does so and I don't see many if any other occurences.

... and that's only four successive year-on-year gains, i.e.  there is not a single example in the dataset of five consecutive yearly gains, so I'm not sure what Tenney's on about.

crandles

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2377 on: May 31, 2018, 03:58:03 PM »
so I'm not sure what Tenney's on about.

Glad I am not the only one.  I did wonder if we were just talking past each other.


How are you ruling out slow rate of decline now the MYI is down to minimal levels (and FYI replaces itself each winter) and some natural variability?

I am not taking your point, crandles.  I have been saying for many years that PIOMAS cannot be right, that the increases in volume from the low must be due to problems with the algorithms.  Of course, there might have been some increase due to natural variation, but the consistent increase over several years cannot have been right, IMO. Tell me how the water-logged slush can be measured in the same way that a similar section of tightly compressed multi-year ice can?  Further, slushy ice cannot be same temperature.  And, there is the stuff that resembles swiss cheese.  How is that being handled?

This seems based on assuming a rapid rate of decline and therefore does not appear to address the issue at hand of how to rule out slow rate of decline and some natural variability.

jai mitchell

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2378 on: May 31, 2018, 04:44:57 PM »
it should be noted that in 2014 PIOMAS version 2.1 was engaged and they revised the reported values of volume (up) back to 2010.

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2379 on: June 01, 2018, 09:20:53 PM »
so I'm not sure what Tenney's on about.

Glad I am not the only one.  I did wonder if we were just talking past each other.


How are you ruling out slow rate of decline now the MYI is down to minimal levels (and FYI replaces itself each winter) and some natural variability?

I am not taking your point, crandles.  I have been saying for many years that PIOMAS cannot be right, that the increases in volume from the low must be due to problems with the algorithms.  Of course, there might have been some increase due to natural variation, but the consistent increase over several years cannot have been right, IMO. Tell me how the water-logged slush can be measured in the same way that a similar section of tightly compressed multi-year ice can?  Further, slushy ice cannot be same temperature.  And, there is the stuff that resembles swiss cheese.  How is that being handled?

This seems based on assuming a rapid rate of decline and therefore does not appear to address the issue at hand of how to rule out slow rate of decline and some natural variability.

http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.1.png

Rob Dekker

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2380 on: June 02, 2018, 10:07:58 AM »
...
This seems based on assuming a rapid rate of decline and therefore does not appear to address the issue at hand of how to rule out slow rate of decline and some natural variability.

http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.1.png

Tenney, it seems to me that crandles is right when he states that your argument "does not appear to address the issue at hand of how to rule out slow rate of decline and some natural variability.".

So what exactly is your point ?

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2381 on: June 02, 2018, 05:37:00 PM »
There actually is a decent test for whether PIOMAS is biased towards the high side.

Let's assume that Extent/Area are decent measures. If PIOMAS were wrong, then you would expect-
-Extent/Area have larger declines than PIOMAS.
-More late summer PIOMAS decline as PIOMAS is forced to catch up with open water.
-Higher thickness values as stated by PIOMAS since the area is not something that can be distorted.

None of these have happened. Extent and Area have also shown flattening in the last few years. PIOMAS has actually shown less late summer volume decline. PIOMAS has had very low thickness numbers the last couple years.

The most likely hypothesis is that PIOMAS is reasonably accurate and recently the ice has actually not melted as much as people thought it would.

magnamentis

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2382 on: June 02, 2018, 10:49:29 PM »
There actually is a decent test for whether PIOMAS is biased towards the high side.

Let's assume that Extent/Area are decent measures. If PIOMAS were wrong, then you would expect-
-Extent/Area have larger declines than PIOMAS.
-More late summer PIOMAS decline as PIOMAS is forced to catch up with open water.
-Higher thickness values as stated by PIOMAS since the area is not something that can be distorted.

None of these have happened. Extent and Area have also shown flattening in the last few years. PIOMAS has actually shown less late summer volume decline. PIOMAS has had very low thickness numbers the last couple years.

The most likely hypothesis is that PIOMAS is reasonably accurate and recently the ice has actually not melted as much as people thought it would.

i find yours a good post.

that said, i don't think they're accurate but for now i think you have good arguments that they are.

i once said that it will be a big "ahaaa...." experience once the flaw will be found.

one argument, while i think it's correct, i'd like to supplement. it's not the melting that i for example think is faster than they say but the freezing i believe is slower than before.

further the state of the ice allows for quite some distribution that would remain above the 15% even though there's less ice-mass. this would as well explain why the number are eventually going down parallely in late summer even though they could both be either incorrect and/or be distracting.

i mean if we have a 100% ice cover and a 20% ice cover that is a huge difference and still they would both still show full extent. as to area i don't thing that current resolutions of several kilometers always allow to measure small the many smaller gaps between smaller ice floes correctly.

what i suspect (dunno) is a sudden drop, once the ever warmer winters, ever warmer waters and ever warmer air will have reduced the remaining ice to a thickness and fragmentation that it will drop below the 15% in masse as well as the gaps between floes will become big enough to be always or better detected by sensors.
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oren

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Re: Latest PIOMAS update (May mid-monthly update)
« Reply #2383 on: June 02, 2018, 11:25:12 PM »
PIOMAS animations show that ir's not extremely wrong. Thick ice is built up gradually, and more importantly thick ice does not disappear overnight into open water, while thin ice does, as you would expect in real life. It is wrong in many details as the comparisons to Cryosat and Ascat show, but in general terms it seems to be behaving correctly.

Wipneus

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Re: Latest PIOMAS update (June)
« Reply #2384 on: June 03, 2018, 08:03:58 PM »
PIOMAS gridded thickness data updated up to 31st May. I calculate a volume on that day of 20.01 [1000 km3 ], 5th lowest for the day.

Attached is the animation for May.

Wipneus

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Re: Latest PIOMAS update (June)
« Reply #2385 on: June 03, 2018, 08:11:44 PM »
Thickness map for 31-May-2018, compared with previous years.

Wipneus

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Re: Latest PIOMAS update (June)
« Reply #2386 on: June 03, 2018, 08:34:05 PM »
Updated volume and volume-anomaly graphs.

Wipneus

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Re: Latest PIOMAS update (June)
« Reply #2387 on: June 03, 2018, 08:38:16 PM »
The Fram export graph.

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Re: Latest PIOMAS update (June)
« Reply #2389 on: June 08, 2018, 09:38:24 AM »
PIOMAS June 2018 has been posted on the ASIB.
Compare, compare, compare

Wipneus

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Re: Latest PIOMAS update (June mid-monthly update )
« Reply #2390 on: June 20, 2018, 05:42:48 PM »
PIOMAS gridded thickness data has updated, last day 15 June. Volume calculated from thickness is now 5th place behind 2017, 2016, 2012 and 2011.

Attached is the animation 0-15 June.

Wipneus

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Re: Latest PIOMAS update (June mid-monthly update )
« Reply #2391 on: June 20, 2018, 05:59:37 PM »
updated volume and volume-anomaly graphs.

Wipneus

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Re: Latest PIOMAS update (June mid-monthly update )
« Reply #2392 on: June 20, 2018, 06:08:26 PM »
Fram export, abound normal for June.

Richard Rathbone

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Re: Latest PIOMAS update (June mid-monthly update )
« Reply #2393 on: June 20, 2018, 06:59:41 PM »
Pretty weak cliff by 2010-2012 standards, but still a cliff. On trend is still looking like a good bet for September.


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Re: Latest PIOMAS update (June)
« Reply #2394 on: June 20, 2018, 07:18:35 PM »
The Fram export graph.

I took the liberty of hacking lumps off from Wipneus' Fram Export graph and putting it against the Greenland Sea area graph. There is some correlation there I think.
"Para a Causa do Povo a Luta Continua!"

oren

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Re: Latest PIOMAS update (June mid-monthly update )
« Reply #2395 on: June 21, 2018, 08:49:00 PM »
I've compiled a few charts... Data courtesy of Wipneus.
Cross-posted from the melting season thread, a chart of Kara Sea volume over the years.

Adam Ash

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Re: Latest PIOMAS update (June mid-monthly update )
« Reply #2396 on: June 28, 2018, 08:28:11 AM »
Regarding the BPIOMAS ice volume charts http://psc.apl.washington.edu/research/projects/arctic-sea-ice-volume-anomaly/

I find it odd that they show the anomalies from a 'base' which advances each year to include all previous years.  Currently the base is 1979-2017.

Given that the annual volume trend is downward, does not this disguise a potentially-exponential down trend compared which would become apparent in the charts if the data was presented in relation to a fixed base of say 1979 to 2009?  Wouldn't that be worth plotting?

Wipneus

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Re: Latest PIOMAS update (June mid-monthly update )
« Reply #2397 on: June 28, 2018, 08:56:05 AM »
Hi Adam,

My anomaly chart (see some posts above) is actually based on the 1979-2009 normal for those reasons. I could make that 1981-2010 so it is compatible with other data series like NSIDC.

You could ask, it could be a leftover from the time when a 30 year period was not available.

Juan C. García

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Re: Latest PIOMAS update (June mid-monthly update )
« Reply #2398 on: June 29, 2018, 05:42:14 AM »
Hi Adam,

My anomaly chart (see some posts above) is actually based on the 1979-2009 normal for those reasons. I could make that 1981-2010 so it is compatible with other data series like NSIDC.

You could ask, it could be a leftover from the time when a 30 year period was not available.


Hi Wipneus.

Your graph says 1979-2001 average.
I think that there is a finger error and it should say 1979-2009, as you say in the past comment.
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.

Wipneus

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Re: Latest PIOMAS update (June mid-monthly update )
« Reply #2399 on: June 29, 2018, 11:07:19 AM »
Your graph says 1979-2001 average.
I think that there is a finger error and it should say 1979-2009, as you say in the past comment.

I actually mentioned the anomaly graph, which uses the latter period. I agree this all lacks consistency, somebody should fix this asap.