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Author Topic: Latest PIOMAS update (December 2019 )  (Read 1080913 times)

oren

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Re: Latest PIOMAS update (April 2019)
« Reply #2750 on: April 03, 2019, 11:12:49 AM »
Thanks for these updates Wipneus.
The volume distribution is disturbing. Looking at the comparison with 2016, most of the positive anomalies are in the Barents and/or facing easy export possibility to the Atlantic.
I will try to dig through the regional files to showcase this situation.

gerontocrat

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Re: Latest PIOMAS update (March)
« Reply #2751 on: April 03, 2019, 12:30:47 PM »
PIOMAS Volume as at 31st March 22,218 KM3.

Here is the volume data presented in the same format as I use for the JAXA ice extent tables and graphs. Down from 7th lowest (15th March) to 4th lowest in the satellite record.

Mostly very much below average gain in the second half of March, and several days of volume loss in the last week. Proof, if it was needed, that a goodly portion of the sea ice area and extent loss recorded in March was genuine melt and not just increased concentration.

On average, maximum on 22nd April. Using average remaining gain over the 2010's years would give a maximum of 22,587 km3, 3rd lowest in the satellite record.
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gerontocrat

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Re: Latest PIOMAS update (April 2019)
« Reply #2752 on: April 03, 2019, 02:28:14 PM »
Some people may use the updated regional data files:

https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional-monthly.txt.gz
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

One of these days I guess I must match the regional volume data from Wipneus to the regional area data from NSIDC. Will my computer cope (it already wheezes doing the regional area and extent data on its own) ?
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Neven

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Re: Latest PIOMAS update (April 2019)
« Reply #2753 on: April 04, 2019, 12:02:10 AM »
New PIOMAS update on the Arctic Sea Ice Blog.
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magnamentis

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Re: Latest PIOMAS update (April 2019)
« Reply #2754 on: April 04, 2019, 12:30:18 AM »
question to the specialists, theoretically i can calculate but there may be hidden traps for a layman, hence i thought to ask:

how much thicker must the ice be to keep the same volume while loosing > 1'000'000km2 in the 2 other dimensions. i assume extent and area won't produce the same result and since i'm not privy with the calculations, i ask that question.

trigger for the question is that each time after a month of steep losses i wonder how it can be that volume could keep level or even increase, is it realistic that the reminder at the same time would grow that much in thickness ?

after all the real area of thickness increase is relatively small, since i think that if the ice is melting at the periphery, there must be some significant range in the midle between the pole and the periphery where ice is melting, just not to zero, keeping thickness and another part where thickness is growing only a little, hence there is not much area left where ice would grow so much to compensate for all the losses.

so much my logics which may be wrong (apparently) and i want to know why i'm apparently erring.

Tealight

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Re: Latest PIOMAS update (April 2019)
« Reply #2755 on: April 04, 2019, 01:21:33 AM »
question to the specialists, theoretically i can calculate but there may be hidden traps for a layman, hence i thought to ask:

how much thicker must the ice be to keep the same volume while loosing > 1'000'000km2 in the 2 other dimensions. i assume extent and area won't produce the same result and since i'm not privy with the calculations, i ask that question.

trigger for the question is that each time after a month of steep losses i wonder how it can be that volume could keep level or even increase, is it realistic that the reminder at the same time would grow that much in thickness ?

after all the real area of thickness increase is relatively small, since i think that if the ice is melting at the periphery, there must be some significant range in the midle between the pole and the periphery where ice is melting, just not to zero, keeping thickness and another part where thickness is growing only a little, hence there is not much area left where ice would grow so much to compensate for all the losses.

so much my logics which may be wrong (apparently) and i want to know why i'm apparently erring.

In simple terms the ice that melts at the edge must be replaced by new ice in the centre. The major problem here is that everyone is only publishing average thickness values for the entire Arctic. The ice that was in Bering Sea and Guld of St Lawrence was probably just 10-20cm thick. So 20cm*1million km2 divided by 10 million km2 for the central Arctic gives you a thickness increase of only 2cm.

PIOMAS is really bad at getting the ice edge right, most of all soutwest Greenland which is pretty much never frozen. It's one of the reason why I developed the high resolution "AMSR2 Snow & Ice Volume". It's not as good for the very thick central Arctic, but much better for thin ice and defining an ice edge.

https://cryospherecomputing.tk/SIT

magnamentis

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Re: Latest PIOMAS update (April 2019)
« Reply #2756 on: April 04, 2019, 01:45:33 AM »
So 20cm*1million km2 divided by 10 million km2 for the central Arctic gives you a thickness increase of only 2cm.

PIOMAS is really bad at getting the ice edge right, most of all southwest Greenland which is pretty much never frozen. It's one of the reason why I developed the high resolution "AMSR2 Snow & Ice Volume". It's not as good for the very thick central Arctic, but much better for thin ice and defining an ice edge.

https://cryospherecomputing.tk/SIT

ok, 2cm appears a very realistic number, i know it's not absolute this number but that doesn't matter because no matter whether it will be 1.5cm or 4cm, both reasonably realistic numbers

thanks for the maths and elaboration about edges and piomas, that was the part that i had no clue about but felt that there is more to it than simple maths.

very much appreciated
« Last Edit: April 04, 2019, 01:20:42 PM by magnamentis »

Ktb

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Re: Latest PIOMAS update (April 2019)
« Reply #2757 on: April 04, 2019, 02:02:50 AM »
The new temperature graphic by the esteemed Zack Labe is quite difficult on the eyes. That yellow is something, that is for sure.
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oren

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Re: Latest PIOMAS update (April 2019)
« Reply #2758 on: April 04, 2019, 05:47:18 AM »
Here are some regional volume charts comparing with previous years.
The Pacific sector looks really bad, the same exact kind of bad that we had in 2018. All 3 seas are near record lows. In 2018 Chukchi melted quite early, but Beaufort held on rather bravely. We will see what 2019 will bring, but it's certainly a disturbing winter trend.
The saving grace is with Bering volume so low, remaining loss is very limited there.

oren

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Re: Latest PIOMAS update (April 2019)
« Reply #2759 on: April 04, 2019, 05:58:00 AM »
On the other side of the Arctic, the Atlantic side looks more or less normal. The bad news here is the possibility of easy transport into killing zones. The Greenland Sea, far above its 2018 record low, hints at ongoing export. Low Pacific sector + active Greenland Sea (and Nares) export + sizable Atlantic volumes = potential for bad year.
« Last Edit: April 04, 2019, 06:09:58 AM by oren »

oren

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Re: Latest PIOMAS update (April 2019)
« Reply #2760 on: April 04, 2019, 06:08:57 AM »
Interestingly, the low minimum years of 2012 and 2016 were both low on the Atlantic side and high on the Bering+Chukchi side at this time of year, while "the years that dodged" 2017 and 2018 were high on the Atlantic side and low on the Bering+Chukchi side. Does this provide some optimism as we head into the melting season? Possibly. The risk is certainly there though, coupled with extent and area in record low territory.

magnamentis

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Re: Latest PIOMAS update (April 2019)
« Reply #2761 on: April 04, 2019, 01:24:48 PM »
Interestingly, the low minimum years of 2012 and 2016 were both low on the Atlantic side and high on the Bering+Chukchi side at this time of year, while "the years that dodged" 2017 and 2018 were high on the Atlantic side and low on the Bering+Chukchi side. Does this provide some optimism as we head into the melting season? Possibly. The risk is certainly there though, coupled with extent and area in record low territory.

an interesting thought while perhaps it worth looking into eventual correlations between summer weather and the two factors (atlantic high & pacific low) you mentioned.

that's of course far beyond my skill but perhaps someone finds your thought interesting enough to look a bit deeper into it.

at least thank to you mentioning it, we can now observe this and the years to come to see whether we shall find a pattern there.

 8)

Juan C. García

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Re: Latest PIOMAS update (April 2019)
« Reply #2762 on: April 04, 2019, 03:49:09 PM »
Not really a PIOMAS topic, but related with the last posts.
As of today, the warmth on the Pacific and Siberia has moved to the Atlantic. The Atlantic Ocean is still cold. I wonder if this coldness on the Atlantic will continue. I believe it will not continue. A warm Atlantic is an important factor on any melting season.
« Last Edit: April 04, 2019, 04:00:56 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.

FishOutofWater

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Re: Latest PIOMAS update (April 2019)
« Reply #2763 on: April 06, 2019, 07:13:57 PM »
The Atlantic side of the Arctic has SSTs that are above normal except for the center of the subpolar gyre which has been cooled by intense storms, strong polar outbreaks, and the outflow of greater than normal amounts of cold fresh water from the Arctic into the Greenland and Labrador seas. There has been a ring of warm salty water around the cold core of the gyre, indicative of active overturning in the Labrador sea. Mercator ocean profiles in the Labrador sea are consistent with greater than normal overturning this winter, but there was also an influx of very cold relatively fresh deep water into the 2000m to 3000m layer, perhaps deep overflow water from the Nordic seas.

That SST map displayed in the comment above is not consistent with DMI, Mercator Ocean and NOAA SST maps. These SST anomaly maps may compare to different 30 year baselines and may have different interpolation schemes. The Mercator anomaly map appears to be on the cool side but the cool water is in the subpolar gyre. An warm anomaly is located where Atlantic water enters the Arctic ocean on the east side the Fram strait. There is a warm anomaly on the west side of Novaya Zemlya This is not good news on the Atlantic side. There has been a powerful outflow of fresh Arctic water through the Nares strait and the CAA into the Labrador sea that has not interrupted the overturning circulation, but has left a cold anomaly in the core of the subpolar gyre. Warm salty water is now pushing up the west coast of Greenland into the ice free waters along the continental shelf margin.

Close comparison of Mercator's 100m map for 5April 2018 with 5April 2019 shows warmer water flowing through the Faroe Shetland channel this year. Increased heat flow through this channel leads to increased heat flow into the Norwegian current in the months that follow. Moreover, the strong storms that have recently entered the Arctic from the Atlantic have advected warm salty water at the 30 to 100 m level into the Barents sea.


What's going on now in the Arctic on the Atlantic side is not good news for the sea ice. We're going to need cool weather in the months ahead to keep this summer from being a very bad one for ice. This very early, apparently record early,  start to volume loss is very bad news.
« Last Edit: April 06, 2019, 07:38:20 PM by FishOutofWater »

Tor Bejnar

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Re: Latest PIOMAS update (April 2019)
« Reply #2764 on: April 15, 2019, 03:27:00 PM »
Image from arctischepinguin via ASI Graphs
I find it interesting that Wipneus's exponential regression has suggested a record low ASI volume below 4K km3 would occur each year since 2011.  Of these, only 2012 had a record low volume below 4K km3.  Is this the  'slow transition' at work or 'statistical noise'?  (I think only time will tell.)

 (Each of the square dot curve segments start with the projected minimum for the year following each year's minimum.  For example, following the 2018 minimum, the curve projects 2019 [dark blue square dot] to have a ASI volume about 2.7K km3 and no ice in 2024.  [The post-2018 curve is in red, not matching the blue dot, but the others all match the curve created at that time.])
« Last Edit: April 15, 2019, 03:38:22 PM by Tor Bejnar »
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oren

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Re: Latest PIOMAS update (April 2019)
« Reply #2765 on: April 15, 2019, 03:39:33 PM »
Quote
Is this the  'slow transition' at work or 'statistical noise'?
I think it's a hint that an exponential regression is not appropriate in this case.

Archimid

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Re: Latest PIOMAS update (April 2019)
« Reply #2766 on: April 15, 2019, 04:00:15 PM »
I think an exponential was the perfect fit from about 2002 to 2012. After and before that period linear fits were better. Sometime in the near future exponential fits will become the better fit again.

I am an energy reservoir seemingly intent on lowering entropy for self preservation.

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Re: Latest PIOMAS update (April 2019)
« Reply #2767 on: April 15, 2019, 10:55:27 PM »
Hi all. This is a new study that I am sure many on this forum will be interested in:

"Arctic sea ice volume variability over 1901–2010: A model-based reconstruction" (PIOMAS-20C): https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-19-0008.1
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jdallen

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Re: Latest PIOMAS update (April 2019)
« Reply #2768 on: April 16, 2019, 08:34:03 AM »
I think an exponential was the perfect fit from about 2002 to 2012. After and before that period linear fits were better. Sometime in the near future exponential fits will become the better fit again.
That suggests to me that the "bound" the exponential trend ran into (and bounced off of) was 3-4000KM2 rather than zero.

It also implies that we've now transitioned into a different system state than existed prior to 2012, where smaller scale feedbacks at high latitude work to preserve a core pack.  In this new system we *may* reach our theoretical BOE, but even when we do, the system could very well pull back to the middle of the new range, and continue to do so. 

I'm wondering we need to look for some other metric to identify a transition taking place out of the current state as we head towards a year round iceless Arctic ocean.
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Neven

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Re: Latest PIOMAS update (April 2019)
« Reply #2769 on: April 16, 2019, 10:16:19 AM »
Hi all. This is a new study that I am sure many on this forum will be interested in:

"Arctic sea ice volume variability over 1901–2010: A model-based reconstruction" (PIOMAS-20C): https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-19-0008.1

Thanks!

From the abstract:

Quote
We compare the magnitude and patterns of sea ice variability between the first half of the 20th century (1901-1940) and the more recent period (1980-2010), both marked by sea ice decline in the Arctic. The first period contains the so-called Early Twentieth Century Warming (ETCW; ∼1920-1940) during which the Atlantic sector saw a significant decline in sea ice volume, but not in the Pacific sector. The sea ice decline over the 1979-2010 period is pan-arctic and six times larger than the net decline during the 1901-1940 period. Sea ice volume trends reconstructed solely from surface temperature anomalies are smaller than PIOMAS-20C suggesting that mechanisms other than warming, such as changes in ice motion and deformation, played a significant role in determining sea ice volume trends during both periods.
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Sam

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Re: Latest PIOMAS update (March)
« Reply #2770 on: April 16, 2019, 11:30:03 AM »
PIOMAS Volume as at 31st March 22,218 KM3.

* vol-2.png (44.45 kB, 662x417 - viewed 1885 times.)

Wow. It is too early to make any firm projections. However, I think this one plot (and the plots of the various ocean segments) is quite suggestive and telling about where we are and where we may be headed.

It appears (presuming there isn't some anomaly) that we may have seen a break and change into a new regime and set of conditions since about March 21. We should know whether that is true or not within just a few weeks.

As with 2007, we may see a dramatic drop from the previous year. We have been on the high side of the statistical error band for a few years. It is unrealistic to think that will continue. A jump to the low side appears as likely as a jump to the mean.

However, if the exponential decline and its error band is anywhere near correct, the low side error band for 2019 is awfully close to an effective 0. This is not a prediction by any means. I still suspect that the exponential decline in volume projected takes us to zero volume in September in about the year 20025. With the low side statistical band, we are likely (though not certain) to reach that a few years before. That could possibly be as soon as 2021-2022.

I suspect too that natural variability (due to the various oscillations ...) have caused us to be abnormally on the high side for a few years and that this has distorted the exponential downward trend upward slightly. And that in turn has moved the most likely intercept with zero ice in September into the future by 1 to 3 years. If true, this suggests a most likely intercept in about the years 2022-2024. and with variation, possible actual first zero ice occurring 2-3 years earlier, so about 2020-2022.

In geologic terms of course, all of these AND all of the IPCC projections are indistinguishable from one another (even those that project zero ice out beyond 2100). We focus so much upon our own lifetimes and timescales, that it is extremely easy to forget that no matter which projections and models best fit reality, that in the geologic scale there is no difference at all.

We are crashing toward a new dynamic for the Earth at a vastly faster pace than any in any time in the ~4.5 billion year geologic record of Earth. The PETM was glacially slow in its transition by comparison. Ironic pun intended. Glaciers aren't so slow any more. And they are getting faster by the day.

Even the most pessimistic of the IPCC authors seem to think that about the years 2030-2040 are the earliest we might see an ice free period in the Arctic summer of the Arctic Ice.  The reality suggests that is folly and that the focus on extent particularly, but also on area, has mislead us to dramatically underestimate the rate at which the world is changing.

And through it all, I believe that the evaluation of what the consequences of that are has been thoroughly missed. Our analyses tend to use variations on what is and to strenuously avoid looking at discontinuous shifts in state and the consequences of those.

It is well worth re-reading and thinking deeply about René Thom's 1960 mathematical treatise "La Théorie des Catastrophes". The treatise is about mathematics, not Arctic ice or the science of the Arctic. But it has potential application. The treatise portrays a series of complex mathematical formulations. Each shows and represents different fold structures for surfaces in multidimensional space which can and sometimes have been found at least in general form to represent real world behaviors in fields as diverse as hysteresis and the behavior of animals when cornered. The theory suggests a very different future than a linear or even exponential progression. It can be used to mathematically describe tipping points with state transitions into new domains, where once a threshold is truly crossed, the system enters a new state, and return to the old state cannot be had by simply backing up. There are huge policy warnings in the implications of that, which our scientific and political leaders seem not at all to grasp.

And depending on which of the many fold equations actually may apply to the transition to an ice free Arctic, one of the warnings is that this may not be the case of simply single state transition. This may result in multiple and successive state transitions, none of which can be reversed directly, and which ultimately take us to some distant and unrecognizable future set of conditions and dynamics. Attempting to return from any one of these to a previous state may itself invoke yet other domain transitions to new and unfamiliar dynamics and processes. Worse yet, we may not be likely to spend a great long time in any one of these, meaning that we may not get enough data to even understand what makes that domain stable, or how to try to stabilize there. We may instead embark on a series of catastrophic shifts, one after the other until we achieve some new stable or quasi-stable dynamic.

Or, if the actual conditions are well represented by the simplest equations we may simply see a large on-going shift from our current domain to a radically different domain. i.e. a tipping point.

Sam
« Last Edit: April 16, 2019, 11:39:58 AM by Sam »

oren

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Re: Latest PIOMAS update (April 2019)
« Reply #2771 on: April 16, 2019, 12:37:18 PM »
Sam, a lot of this duscussion belongs in the "When will the Arctic go ice-free?" thread.

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Re: Latest PIOMAS update (April 2019)
« Reply #2772 on: April 16, 2019, 12:52:55 PM »
I think an exponential was the perfect fit from about 2002 to 2012. After and before that period linear fits were better. Sometime in the near future exponential fits will become the better fit again.
That suggests to me that the "bound" the exponential trend ran into (and bounced off of) was 3-4000KM2 rather than zero.

Let me once again point to Tietsche et al 2011.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010GL045698

DO NOT LOOK AT THE TIME FRAME
DO NOT LOOK AT THE SPECIFIC "ICE FREE" THOUGHT EXPERIMENT

The point to make here is that Figure 1 shows the "shape" of the decline towards zero, as predicted by a full climate model with atmosphere, ocean, geography and bathymetry included.  It is not linear, exponential, Gompertz or any such simple shape.  It is conditioned by the ocean currents, land masses and airflow patterns.  These conspire to produce a "stepped" decline with plateaus at ~4.5 million km^2 and ~2 million km^2 mean September extent.

The first plateau corresponds to an Arctic where (roughly speaking) the "shallow rim" seas melt out, but ice cover is retained over the deep central triangle.  The second plateau corresponds to an Arctic which is mostly ice-free but has a remnant core of ice crammed up against north Greenland/Ellesmere. Since 2007, we have been basically bumping along the first of these plateaus, as is clear from the September record.
http://nsidc.org/arcticseaicenews/2018/10/

It's anybody's guess as to when we fall off and plummet down to the second, but the Tietsche paper suggests it will be some time in the next decade. Given the rather wide standard deviation, the "ice free" threshold of 1 million could be hit at any point thereafter.

crandles

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Re: Latest PIOMAS update (April 2019)
« Reply #2773 on: April 16, 2019, 03:33:56 PM »
Let me once again point to Tietsche et al 2011.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010GL045698

DO NOT LOOK AT THE TIME FRAME
DO NOT LOOK AT THE SPECIFIC "ICE FREE" THOUGHT EXPERIMENT

The point to make here is that Figure 1 shows the "shape" of the decline towards zero, as predicted by a full climate model with atmosphere, ocean, geography and bathymetry included.  It is not linear, exponential, Gompertz or any such simple shape.  It is conditioned by the ocean currents, land masses and airflow patterns.  These conspire to produce a "stepped" decline with plateaus at ~4.5 million km^2 and ~2 million km^2 mean September extent.

Why believe shape shown by that one model?
If other models were showing it, then it would seem reliably indicated by models and it would be sensible to believe it.



Don't these other models more reliably show a gompertz shape?

gerontocrat

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Re: Latest PIOMAS update (April 2019)
« Reply #2774 on: April 16, 2019, 05:13:05 PM »

DO NOT LOOK AT THE TIME FRAME
DO NOT LOOK AT THE SPECIFIC "ICE FREE" THOUGHT EXPERIMENT

The point to make here is that Figure 1 shows the "shape" of the decline towards zero, as predicted by a full climate model with atmosphere, ocean, geography and bathymetry included.  It is not linear, exponential, Gompertz or any such simple shape.  It is conditioned by the ocean currents, land masses and airflow patterns.  These conspire to produce a "stepped" decline with plateaus at ~4.5 million km^2 and ~2 million km^2 mean September extent.

Why believe shape shown by that one model?
If other models were showing it, then it would seem reliably indicated by models and it would be sensible to believe it.

Don't these other models more reliably show a gompertz shape?
Arguing in the PIOMAS thread about the future of Arctic sea ice with reference to extent models?

Anyway, here is a volume graph that hasn't seen the light of day for a bit.
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crandles

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Re: Latest PIOMAS update (April 2019)
« Reply #2775 on: April 16, 2019, 05:35:13 PM »

Arguing in the PIOMAS thread about the future of Arctic sea ice with reference to extent models?

Anyway, here is a volume graph that hasn't seen the light of day for a bit.

A cubic equation that indicates a slight increase from 2024 and will later quickly shoot upwards? Seems a odd thing to include with that criticism.

Yes there is an issue with showing extent graphs to demonstrate expected volume trend. But does it undermine my point?

If volume loses maintained linear loss rate, then extent graphs would have to show accelerating rate of loss to catch up. However if extent graphs show declining rate of decline then volume graph will have to slow down more sharply. So I think the difference between volume and extent strengthens my point.

The other point: Picking one particular model and saying step changes at these points seems a poor method compared with looking at shape from many models. This also seems to survive.

But I will admit this is getting off topic, more suited to 'when ice free'.

FishOutofWater

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Re: Latest PIOMAS update (April 2019)
« Reply #2776 on: April 16, 2019, 06:12:57 PM »
None of those curves have any predictive power, in my opinion. Weather and changes in the influx and outflow of water masses will determine what happens to area, extent and volume over the coming years. Weather is always factor number 1.

Will there be a mid month volume update? I'm very interested to see how early the drop in volume begins this year.

Sam

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Re: Latest PIOMAS update (April 2019)
« Reply #2777 on: April 16, 2019, 07:21:46 PM »
Sam, a lot of this duscussion belongs in the "When will the Arctic go ice-free?" thread.

Ah yes, the age old dilemma and arguments between lumpers and splitters.

There are those who infinitely divide the world into bits, and those that don't. I don't. Period. Full stop.

The world is not a divided place. It is an interconnected whole. We can try (and fail repeatedly) to divide the world and our discussions neatly into areas and piles. In the process we risk losing sight of the key factors and warnings, which is precisely my point.

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Re: Latest PIOMAS update (April 2019)
« Reply #2778 on: April 16, 2019, 09:06:09 PM »
Sam, a lot of this duscussion belongs in the "When will the Arctic go ice-free?" thread.

Ah yes, the age old dilemma and arguments between lumpers and splitters.

There are those who infinitely divide the world into bits, and those that don't. I don't. Period. Full stop.

The world is not a divided place. It is an interconnected whole. We can try (and fail repeatedly) to divide the world and our discussions neatly into areas and piles. In the process we risk losing sight of the key factors and warnings, which is precisely my point.

hear hear... trying to hing at that dilemma for years but the experts (narrow minded) will never let it happen and they're a majority.

the last sentence does not point to the person who posted above, it's a general statement in reply to the post i quoted.

+1 _ seconding that as long as discussions are not mixed up to a degree that it becomes impossible to focus on a specific topic that is part of the whole of course ;)

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Re: Latest PIOMAS update (April 2019)
« Reply #2779 on: April 16, 2019, 09:17:22 PM »
We should be mindful that stickied threads in particular have a lot of readers who don't actively participate, so churning unrelated discussion in them is a lot of noise for people who specifically just want to see PIOMAS numbers for example.

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Re: Latest PIOMAS update (April 2019)
« Reply #2780 on: April 16, 2019, 11:33:00 PM »
Yes, let's all just shut up until Wip posts the mid-month numbers (I'm also very curious to see those).
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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2781 on: April 19, 2019, 03:57:34 PM »
PIOMAS has updated the gridded thickness data up the 15th of April. My calculated volume for that day is 20.74 22.46 [1000km3]. This is third lowest day-value behind 2017 and 2018.

Here is the animation for April sofar.

FIXED: correct volume
« Last Edit: April 19, 2019, 04:34:51 PM by Wipneus »

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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2782 on: April 19, 2019, 04:15:14 PM »
What is the difference from 2017 & 2018?  For example, is it 1% above or 10%??

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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2783 on: April 19, 2019, 04:18:11 PM »
Wouldn't 20.74 put it below 2018?

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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2784 on: April 19, 2019, 04:30:42 PM »
Fram volume export appears to have been very low in the first half of the month.

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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2785 on: April 19, 2019, 04:40:57 PM »
The daily volume and volume-anomaly graphs.

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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2786 on: April 19, 2019, 04:44:51 PM »
Wouldn't 20.74 put it below 2018?

Indeed, I took it from the wrong (sorted) table, 20.74 is for 2017 (lowest value). The corrected value (22.46) is in the post now.

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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2787 on: April 19, 2019, 04:51:12 PM »

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Re: Latest PIOMAS update (March)
« Reply #2788 on: April 19, 2019, 05:40:20 PM »
PIOMAS Volume as at 15 April  22,459 KM3.

Here is the volume data presented in the same format as I use for the JAXA ice extent tables and graphs. Down from 4th lowest (31 March) to 3rd lowest in the satellite record.

On average, maximum on 22nd April. Using average remaining gain over the 2010's years would give a maximum of 22,488 km3, 3rd lowest in the satellite record.

The next post will be looking at the melting season, I presume (too much?).
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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2789 on: April 19, 2019, 05:57:10 PM »
Wouldn't 20.74 put it below 2018?

looks like around 2 weeks ahead if we look at when the volume max has been reached this year.

beside the sheer numbers that make this 3rd place i can imagine that the fact of very early volume max has a deeper meaning and cold have a significant impact, depending on the weather of course, as usual ;)
« Last Edit: April 19, 2019, 08:51:36 PM by magnamentis »

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Re: Latest PIOMAS update (March)
« Reply #2790 on: April 19, 2019, 05:57:38 PM »

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Re: Latest PIOMAS update (March)
« Reply #2791 on: April 22, 2019, 10:24:01 PM »
(too much?)

Hell no! :)
So here is the start of some more.

I have taken the regional seas daily volume data from 2000 from the WIPNEUS file to produce volume graphs for individual seas. I am now matching that volume against the NSIDC area data for individual seas to produce the rough calculation of average thickness for each sea. It is taking some time, the laptop is screaming in protest.

So here are just 2 graphs - for the 3.2 million km2 Central Arctic Basin. Note how thickness maximum is a bit later than volume maximum, and that there is a real cliff at the beginning of June on the thickness graph.
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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2792 on: April 23, 2019, 09:15:58 PM »
Here are the extent, area, volume and thickness graphs for the Bering Sea. At times when area and volume approach zero, the thickness calculation becomes a bit random- i.e. meaningless. I had to get rid of a lot of this meaningless data in the summer months.

As yet, I am not sure what meaningful observations can be made from comparing these 4 different measures of sea ice.
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Re: Latest PIOMAS update (April 2019 mid-monthly update)
« Reply #2793 on: April 23, 2019, 09:44:42 PM »
Here are the extent, area, volume and thickness graphs for the Bering Sea. At times when area and volume approach zero, the thickness calculation becomes a bit random- i.e. meaningless. I had to get rid of a lot of this meaningless data in the summer months.

As yet, I am not sure what meaningful observations can be made from comparing these 4 different measures of sea ice.
And the meaningful observation is... Noise... which is the state the Bering has been in for pretty much the last month.
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Re: Latest PIOMAS update (May 2019)
« Reply #2794 on: May 04, 2019, 08:34:52 AM »
PIOMAS gridded thickness data has updated. AFAICS the official volume data net yet.
Volume on 30th April was 22.34 [1000 km3]. This is the fourth lowest but the differences with third and fifth place are so small that the official volume data may disagree.

Here is the animation for April.

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Re: Latest PIOMAS update (May 2019)
« Reply #2795 on: May 04, 2019, 09:02:22 AM »
Hard to believe.
Salt accumulations by wave actions produce false positive Results.

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Re: Latest PIOMAS update (May 2019)
« Reply #2796 on: May 04, 2019, 09:58:27 AM »
Here are the volume and volume-anomaly graphs. The 2019 volume  is very close with 2011, 2016 and 2018. Virtually sharing second (lowest) place.

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Re: Latest PIOMAS update (May 2019)
« Reply #2797 on: May 04, 2019, 10:01:43 AM »
Fram export (volume) was on average low in April.

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Re: Latest PIOMAS update (March)
« Reply #2799 on: May 04, 2019, 01:20:05 PM »
PIOMAS Volume as at 30 April  22,459 KM3.

Once again, courtesy of data from Wipneus, is the volume data presented in the same format as I use for the JAXA ice extent tables and graphs.

Maximum was on 22nd April at 22.492 km3, 3rd lowest in the satellite record.

At 30th April volume was 4th lowest in the satellite record by a smidgeon. Everything has been very average in April.
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