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Author Topic: Latest PIOMAS update (April)  (Read 415311 times)


FishOutofWater

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Re: Latest PIOMAS update (April)
« Reply #1601 on: April 14, 2017, 06:03:45 PM »
Repeated strong high latitude atmospheric blocking, combined with persistent low pressure over the Arctic ocean drove warm air from the Pacific and Atlantic oceans, repeatedly over the Arctic. This lead to record warmth over the Arctic ocean and inhibited sea ice growth. Moreover, the pattern favors increased warm Atlantic water inflow through the Fram strait.

Thus PIOMAS now shows record low sea ice volume for March.

PIOMAS is the best physical model we have, but it does not predict the weather. No curve fitting has the physics of PIOMAS. The arguments over curve fitting are meaningless.

This winter's weather was unprecedented. We're in uncharted waters. It's going to take atmospheric scientists several years, at least, to understand what's happening with the unprecedented weather.

Research to date indicates that there may be a feed back between the low sea ice volume and the weather. Thus we're dealing with a possible tipping point, because the system is potentially unstable.

Which brings up back to watching the PIOMAS thickness results. The science to predict accurately what the sea ice will look like two or three summers from now does not yet exist. The best we can do is to make accurate observations. Predictions are not reliable.

prokaryotes

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Re: Latest PIOMAS update (April)
« Reply #1602 on: April 14, 2017, 06:20:40 PM »
And then there is the Arctic air intrusion into lower latitudes, ie. The highs of 25 ºC last week will seem like a distant memory as it turns colder this #EasterWeekend, as cooler air comes down from the north https://twitter.com/metoffice/status/852902667064102912 Like to read a bit more updates on the historical perspective on this, and frequency and such, and in relation to the Polar Vortex pressure.

Rick Aster

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Re: Latest PIOMAS update (April)
« Reply #1603 on: April 14, 2017, 06:56:33 PM »
And then there is the Arctic air intrusion into lower latitudes
...
Like to read a bit more updates on the historical perspective on this, and frequency and such, and in relation to the Polar Vortex pressure.


You won't find much of that in the Cryosphere part of the forum, which is mostly about the higher latitudes, but try the Consequences part, particularly "Topic: Weird Weather and anecdotal stories about climate change" http://forum.arctic-sea-ice.net/index.php/topic,323.0.html

prokaryotes

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Re: Latest PIOMAS update (April)
« Reply #1604 on: April 14, 2017, 07:02:25 PM »
You won't find much of that in the Cryosphere part of the forum...

Thanks, was just mentioning it because of what appears to be FOOW's excellent blog -
 and thought it was worth mentioning because of the interconnections http://www.dailykos.com/blog/FishOutofWater

oren

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Re: Latest PIOMAS update (April)
« Reply #1605 on: April 14, 2017, 07:33:47 PM »
Just a quick one. 2017 has build a big lead over 2012 in the race for the lowest annual minimum (Arctic Sea Ice) volume.

The graph shows that most of the lead was gained in the freezing season: end-October/begin-November, followed by a smaller spurt in December. The bump in February, followed by the slow decrease in March may or may not be regarded as "noise". No regression toward the mean indeed.
I too think this chart is very disturbing. The low autumn volume should have caused the ice to thicken more later, but it didn't. And the continued strong export of old ice into the Atlantic gives good cause to believe that end-April PIOMAS numbers will be as bad.
My only (slim) hope at this stage is that PIOMAS somehow made a mistake in concentrating all the volume in that moving "blob" further to the north of Greenland, while past years, and other models such as Hycom, put it closer to Greenland in the protected Lincoln Sea. In which case more volume might actually emerge out of the winter than the number claimed by PIOMAS.
btw the FDD anomaly shows a similar trend, most of it happened in the autumn and only a little was added over the winter - but there was no mean reversion.

AndrewB

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Re: Latest PIOMAS update (April)
« Reply #1606 on: April 14, 2017, 08:07:55 PM »
...
Thus PIOMAS now shows record low sea ice volume for March.
...

Actually just look at the chart posted by prokaryotes in the comment just before yours, and you'll notice that PIOMAS has been showing record low Arctic sea ice volume for the months of December 2016, and January, February and March 2017.

: FishOutofWater
...
Predictions are not reliable.

Here is one prediction that I am reasonably confident about: PIOMAS for April 2017 will also be a record monthly low.  ;)

prokaryotes

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Re: Latest PIOMAS update (April)
« Reply #1607 on: April 14, 2017, 08:31:20 PM »
Will there be impact on the Greenland surface melt, like we had in 2012? So far not much? (tick 2017 to compare 2012 with 2017 in NSIDC interactive graph)
http://nsidc.org/greenland-today/greenland-surface-melt-extent-interactive-chart

Notice NSIDC stated April 3, 2017
Daily updates have resumed for the 2017 melt season. Bit puzzling, according to the data not a single melt day so far?

In recent decades, the Greenland ice sheet has experienced increased surface melt. However, the underlying cause of this increased surface melting and how it relates to cryospheric changes across the Arctic remain unclear. Here it is shown that an important contributing factor is the decreasing Arctic sea ice. Reduced summer sea ice favors stronger and more frequent occurrences of blocking-high pressure events over Greenland. Blocking highs enhance the transport of warm, moist air over Greenland, which increases downwelling infrared radiation, contributes to increased extreme heat events, and accounts for the majority of the observed warming trends. These findings are supported by analyses of observations and reanalysis data, as well as by independent atmospheric model simulations using a state-of-the-art atmospheric model that is forced by varying only the sea ice conditions. Reduced sea ice conditions in the model favor more extensive Greenland surface melting. The authors find a positive feedback between the variability in the extent of summer Arctic sea ice and melt area of the summer Greenland ice sheet, which affects the Greenland ice sheet mass balance. This linkage may improve the projections of changes in the global sea level and thermohaline circulation.
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0391.1
« Last Edit: April 14, 2017, 08:37:35 PM by prokaryotes »

Neven

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Re: Latest PIOMAS update (April)
« Reply #1608 on: April 14, 2017, 10:58:36 PM »
From now on I only want to see comments on PIOMAS now/near real-time and nothing about Greenland or other tangential stuff. I have put on my snipping gloves.
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Tigertown

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Re: Latest PIOMAS update (April)
« Reply #1609 on: April 14, 2017, 11:13:04 PM »
The Open Thread is getting lonely. Why not use it.

https://forum.arctic-sea-ice.net/index.php/topic,1884.250.html#lastPost

Shared Humanity

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Re: Latest PIOMAS update (April)
« Reply #1610 on: April 14, 2017, 11:44:27 PM »
As of April 13, Sea Ice Extent, at 13,155,325 km2, is in a dead heat with 2016. Meanwhile PIOMASS shows that volume is 2000 cubic km below 2016. We have a whole lot of thin ice out there. If we want to understand how this melt season will play out, we need to look at where the CAB will go 'early ice free' and how early this will happen. I am particularly concerned with those areas that are dominated with ice below 2 meters thick. There are large areas where ice is no more than 1.5 meters thick.

Obviously, the FDD anomaly did a whole lot of damage to ice in the CAB and warm winters are becoming the new normal.

Would not be surprised if we see record lows in all three metrics at the end of this melt season.
« Last Edit: April 14, 2017, 11:51:10 PM by Shared Humanity »

rboyd

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Re: Latest PIOMAS update (April)
« Reply #1611 on: April 15, 2017, 12:57:49 AM »
<snip, wrong place: N.>
« Last Edit: April 15, 2017, 10:28:04 AM by Neven »

Jim Williams

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Re: Latest PIOMAS update (April)
« Reply #1612 on: April 15, 2017, 01:10:25 AM »
<snip, wrong place: N.>

<snip, wrong place: N.>

« Last Edit: April 15, 2017, 10:28:29 AM by Neven »

Wipneus

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Re: Latest PIOMAS update (April)
« Reply #1613 on: April 15, 2017, 03:05:56 PM »
Andreas T asked me the following question:

: Andreas T date=1492254011
I am using AMSR layers on worldview to get estimates of area export through Fram. To make sure what I do is comparable to your PIOMAS volume exports, can you tell me (posting on the forum perhaps) what the reference points for theses values are? I.e. boundary, and time intervals (end of month or mid month)
Thank you for all the work you are doing on this
Andreas

Hi Andreas,

Attached is a map with the PIOMAS grid on it.

I choose the pink pixels because they are aligned on a meridian in the PIOMAS grid and bridge the Strait in the least number of grid cells (there are a few more). Not that it matters a lot, calculating transport at another "crossing" makes little difference.

PIOMAS data gives me:
- average ice thickness in each cell
- velocity in the direction of the crossing
- cell dimensions, in this case the cell width (in the direction of the crossing)

the volume transport per cell is given by:

  thickness*velocity*cell-width

Summing the cells shown in the map, gives total volume export

I can do this monthly thickness and velocity data. Daily data is possible as well but the noise is incredible, filtering gives results similar to using monthly data.

 




Shared Humanity

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Re: Latest PIOMAS update (April)
« Reply #1614 on: April 15, 2017, 04:01:41 PM »
You are a Wizard!

Andreas T

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Re: Latest PIOMAS update (April)
« Reply #1615 on: April 15, 2017, 08:08:54 PM »
thank you Wipneus, nice to see a little "under the bonnet" of the PIOMAS model

The purpose of my effort here is to get a comparison via a different approach of the current rate of export with other years (although this is too cumbersome to do for a lot more months)
While AMSR2 data is only available since 2016, there are AMSRE data shown on worldview and I picked 2009 as an example of high export in the PIOMAS output.

I am attaching an animation of Feb / Mar / Apr 2009 with ice area which crossed 80N before 1. May marked by red dots and orange lines at end of month
a bit of work in progress but I want to see if this works before I continue
position of the dots on 2. Feb 2009:
 84,9N / 28.2W
 85.7N / 2.9W
 85.2N/ 22.8E
 eastern edge 25E
« Last Edit: April 16, 2017, 12:19:54 PM by Andreas T »

Andreas T

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Re: Latest PIOMAS update (April)
« Reply #1616 on: April 15, 2017, 08:13:42 PM »
gif does not seem to play, any suggestions?

Hyperion

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Re: Latest PIOMAS update (April)
« Reply #1617 on: April 16, 2017, 01:21:07 AM »
Hmmm. With the kill zone extending all the way to FJL, and Bering and Nares etc also being very active, I wonder if the real toll might be closer to 3x what Frams been gobbling.
the other concern I have is how much of the surface water is being exported and lost with that Ice. the Ice may only average ¬2m, but is 10m or even 20m of low salinity water going along  with it?  ???
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Wipneus

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Re: Latest PIOMAS update (April)
« Reply #1618 on: April 16, 2017, 08:46:52 AM »
gif does not seem to play, any suggestions?

Forum software is picky/buggy. Change something to the file, eg shave of some pixels and it may work.

Andreas T

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Re: Latest PIOMAS update (April)
« Reply #1619 on: April 16, 2017, 12:47:56 PM »
Thanks, made some small changes, working now.
@Hyperion, no the other outlets to the Atlantic / Barents Sea definitely carry much less export.
have a look at https://www.climate.gov/news-features/videos/old-ice-arctic-vanishingly-rare
or see http://ocean.dmi.dk/arctic/icedrift/index.uk.php for more recent movement

gerontocrat

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Re: Latest PIOMAS update (April)
« Reply #1620 on: April 25, 2017, 03:25:11 PM »
Being addicted to volume data, while waiting for the PIOMAS monthly update I go to ArctischePinguin to pick up the Jaxa-amsr2-volume graph. It shows a 2000 km3 increase in volume at the beginning of April which as yet persists.

This is in complete contrast to the numerous physical observations, images and animations posted all over the ASIF Arctic sea ice threads indicating the disastrous state of the ice-cap . I am confused (situation normal).


Shared Humanity

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Re: Latest PIOMAS update (April)
« Reply #1621 on: April 25, 2017, 03:29:04 PM »
Being addicted to volume data, while waiting for the PIOMAS monthly update I go to ArctischePinguin to pick up the Jaxa-amsr2-volume graph. It shows a 2000 km3 increase in volume at the beginning of April which as yet persists.

This is in complete contrast to the numerous physical observations, images and animations posted all over the ASIF Arctic sea ice threads indicating the disastrous state of the ice-cap . I am confused (situation normal).

Have gone through life confused much of the time.

Juan C. García

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Re: Latest PIOMAS update (April)
« Reply #1622 on: April 25, 2017, 03:59:31 PM »
Being addicted to volume data, while waiting for the PIOMAS monthly update I go to ArctischePinguin to pick up the Jaxa-amsr2-volume graph. It shows a 2000 km3 increase in volume at the beginning of April which as yet persists.

This is in complete contrast to the numerous physical observations, images and animations posted all over the ASIF Arctic sea ice threads indicating the disastrous state of the ice-cap . I am confused (situation normal).

Have gone through life confused much of the time.

It is normal to have the maximum extent in March. However, it is also normal that the ice thickness increases until April. For that reason, it is normal that the maximum in volume happens in April.
Which is the best answer to Sep-2012 ASI lost?
50% [NSIDC extent vs 1979-2000] or
80% [Orig. PIOMAS volume vs 1979, 77.6% with corrections]

Volume is harder to measure than extent, but 3D is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC official trends underestimate the real speed of ASI lost.

jai mitchell

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Re: Latest PIOMAS update (April)
« Reply #1623 on: April 25, 2017, 04:03:11 PM »
There is also some possibility that the abnormally low thickness average could produce conditions for later season growth at peak.
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crandles

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Re: Latest PIOMAS update (April)
« Reply #1624 on: April 25, 2017, 04:06:40 PM »

It is normal to have the maximum extent in March. However, it is also normal that the ice thickness increases until April. For that reason, it is normal that the maximum in volume happens in April.


PIOMAS has extent maximum in March, volume maximum mid April and average thickness maximum late April / early May.



ie after max volume, extent is going down faster than volume so that volume/extent continues to increase for a short while.

Juan C. García

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Re: Latest PIOMAS update (April)
« Reply #1625 on: April 25, 2017, 04:15:58 PM »
Piomas volume monthly data (1000 km3), with minimums highlighted. I will expect that 2017 will have new minimum records on April and May, at least. That will make seven consecutive records (from November 2016 to May 2017). Afterwards, the minimum was stablish on 2012. So 2017 will be in direct competence with 2012 minimum, from June to October.
Which is the best answer to Sep-2012 ASI lost?
50% [NSIDC extent vs 1979-2000] or
80% [Orig. PIOMAS volume vs 1979, 77.6% with corrections]

Volume is harder to measure than extent, but 3D is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC official trends underestimate the real speed of ASI lost.

oren

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Re: Latest PIOMAS update (April)
« Reply #1626 on: April 25, 2017, 05:24:46 PM »
Thank you Juan for this excellent table. I love it.
Eyeballing the numbers for the hundredth time, I would hazard the following guesses regarding upper volume limits, based on past performance and unreliable gut feeling:
April 20.800
May 19.800
June 15.800 (still a record though barely)
In terms of probability I wouldn't be surprised to see lower numbers, even much lower, but I would be surprised to see higher numbers.

crandles

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Re: Latest PIOMAS update (April)
« Reply #1627 on: April 25, 2017, 07:16:30 PM »
I get different numbers

:
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg
2007 18.377 20.863 23.031 23.764 23.078 19.11 12.038 7.582 6.528 7.135 10.472 14.238 15.480
2008 18.58 21.579 23.863 24.995 24.102 20.498 14.061 9.154 7.246 8.309 11.759 15.197 16.576
2009 18.852 21.729 23.827 24.957 23.851 19.649 12.733 8.235 6.923 7.664 10.813 14.242 16.083
2010 17.723 20.631 23.121 24.103 22.181 17.044 10.153 5.888 4.748 6.237 9.535 12.984 14.486
2011 16.261 19.37 21.421 22.51 21.108 16.403 9.457 5.453 4.484 5.754 9.316 13.052 13.675
2012 16.945 19.63 21.964 23.13 21.677 15.896 9.177 4.923 3.789 5.036 8.276 12.195 13.512
2013 15.862 19.376 22.001 23.131 21.839 17.447 10.446 6.361 5.483 6.996 10.13 13.85 14.373
2014 17.46 19.887 21.838 22.946 21.878 17.6 11.88 8.114 6.975 8.201 11.541 15.13 15.255
2015 18.502 21.508 23.244 24.239 23 18.467 11.55 7.047 5.854 7.052 10.354 14.061 15.364
2016 17.234 19.633 21.559 22.472 20.993 16.408 10.169 5.897 4.533 5.537 7.882 11.266 13.591
2017 14.695 17.414 19.632
Projection w max 20.798 20.112 16.508 10.788 7.022 6.144 7.657 11.219 15.138 12.566
Projection w min 20.365 18.443 12.662 5.59 0.683 -1.225 -0.618 1.727 5.111 9.488

We seem likely to get a record low average for year even following max changes from one month to the next from last 10 years.

oren

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Re: Latest PIOMAS update (April)
« Reply #1628 on: April 25, 2017, 08:45:25 PM »
In guessing I relied on the peculiar fact that in all past years in the table May volume did not exceed March volume by more than 150250, regardless of April variability.
« Last Edit: Today at 12:36:22 AM by oren »

Juan C. García

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Re: Latest PIOMAS update (April)
« Reply #1629 on: April 25, 2017, 11:45:18 PM »
Thank you Crandles and Oren for your comments. I didn't notice before that the thickness grows until early May.
Regarding the values that I used on Piomas Monthly Volume, I took it directly from Piomas, so they are the official monthly data.
I made a forecast, looking to the max and min change between a given month and March, for each year, on 2007-2016.
So the maximum value for September is if 2017 follows the path of 2014, which will bring a value of 4.77k km3.
The minimum value for September is if 2017 follows the path of 2010, which will bring a value of only 1.26k km3.
The average of both values is 3.01k km3, that will be a huge record, if it happens.  :o
In both cases, max and min, the average of the year will be less than the average of 2012: 13.55k km3 (2012) versus 13.12k km3 (max) and 11.06k km3 (min).
Which is the best answer to Sep-2012 ASI lost?
50% [NSIDC extent vs 1979-2000] or
80% [Orig. PIOMAS volume vs 1979, 77.6% with corrections]

Volume is harder to measure than extent, but 3D is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC official trends underestimate the real speed of ASI lost.

crandles

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Re: Latest PIOMAS update (April)
« Reply #1630 on: April 25, 2017, 11:57:39 PM »
Regarding the values that I used on Piomas Monthly Volume, I took it directly from Piomas, so they are the official monthly data.

I averaged the daily volume numbers (well I trusted most of the numbers from https://sites.google.com/site/arctischepinguin/home/piomas ). The differences look to be too much for rounding down to 3dp and my numbers are higher by more than .03 or slightly more than .001 per day. Not sure why there would be that difference. Slightly odd but not important as the systematic error will be far greater than that.

Juan C. García

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Re: Latest PIOMAS update (April)
« Reply #1631 on: Today at 12:57:46 AM »
Regarding the values that I used on Piomas Monthly Volume, I took it directly from Piomas, so they are the official monthly data.


I averaged the daily volume numbers (well I trusted most of the numbers from https://sites.google.com/site/arctischepinguin/home/piomas ). The differences look to be too much for rounding down to 3dp and my numbers are higher by more than .03 or slightly more than .001 per day. Not sure why there would be that difference. Slightly odd but not important as the systematic error will be far greater than that.


I took the Monthly data directly from Piomas. First you have to register on the second download (PIOMAS Monthly Ice Volume Data, 1979-present). Even that it says it is optional, it doesn't send the link unless you write your aswers:

http://psc.apl.uw.edu/research/projects/arctic-sea-ice-volume-anomaly/data/
Which is the best answer to Sep-2012 ASI lost?
50% [NSIDC extent vs 1979-2000] or
80% [Orig. PIOMAS volume vs 1979, 77.6% with corrections]

Volume is harder to measure than extent, but 3D is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC official trends underestimate the real speed of ASI lost.