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Author Topic: Latest PIOMAS update (July 2020)  (Read 1192331 times)

Richard Rathbone

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Re: Latest PIOMAS update (September)
« Reply #750 on: September 07, 2015, 08:54:29 PM »
Quote
Given all this I don't expect August to see a loss of much over 2500 km3, unless PIOMAS has some melting momentum factor from July that bleeds through into August.

2629 km3 it is. Interesting...  :)

It looks like the dip in the anomaly trace came about 23rd-26th August, which would implicate the cyclone (and subsequent accelerated bottom melt) in the larger-than-expected volume decline.

Accelerated bottom melt means PIOMAS has some melting momentum factor from August that bleeds through into September.

Sunlight goes into the sea heating up the near surface layer during the early part of the season and this mixes upwards to melt ice later in the season. August cyclones can bring it up faster (notably in 2012) and result in melting happening earlier than it otherwise would. On the other hand if the Beaufort Gyre is in full swing, it takes a significant amount of this heat downwards resulting in rather less melting.

Wipneus

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Re: Latest PIOMAS update (September Interim)
« Reply #751 on: September 18, 2015, 07:47:34 AM »
PSC has released an interim update for reaching the 2015 minimum (h/t Michael Yorke).

On the official PIOMAS page page they comment:

Quote
The sea ice extent minimum for 2015 was likely reached on Sept 11. Sea ice volume minimum was reached a day later with a total volume of 5670 km3 . This  value is about 1200 km3 below the volume minimum of the 2014 which showed a subtantial rebound in ice volume. The value for 2015 is 300 km3 above the value for 2013 and constitutes a continuation of the long-term declining trend (see fig 1) with shorter term  variability in both directions (e.g. 2012 and 2014).

(color: PSC)

Just the volume data is available, not the gridded thickness.
I will update the September minimum graphics shortly.

Wipneus

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Re: Latest PIOMAS update (September Interim)
« Reply #752 on: September 18, 2015, 08:51:32 AM »
The September minimum graphics updated with the (prelim) minimum of 2015.

In the bunch of curve fits most projected melt-out ( curve intersects the volume=0 line) dates have increased by about one year.

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Re: Latest PIOMAS update (September Interim)
« Reply #753 on: September 18, 2015, 09:09:21 AM »
While you can conclude that most "faster than linear" curve fitting exercises seem to be unreliable forecasters of the final melt-out, a linear fit to the full PIOMAS data shows that the post 2012 "recovery" hardly brings the volume above the projected number. Contrary, the data still shows that the rate of decline is more than linear.
The linear projection predicts that 2012 levels will be the norm in 6-7 years.

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Re: Latest PIOMAS update (September Interim)
« Reply #754 on: September 18, 2015, 09:11:02 AM »
For completeness here are the exponential and gompertz fits.

Neven

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Re: Latest PIOMAS update (September Interim)
« Reply #755 on: September 18, 2015, 09:25:59 AM »
Thanks, Wipneus!
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slow wing

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Re: Latest PIOMAS update (September Interim)
« Reply #756 on: September 18, 2015, 11:05:06 AM »
Yep, thanks Wipneus!

Thanks also to the PIOMAS people for releasing the result so promptly. Appreciated!

Richard Rathbone

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Re: Latest PIOMAS update (September Interim)
« Reply #757 on: September 18, 2015, 11:24:58 AM »
Is using 1997 as the starting year for the linear fit supported by any method such as change point analysis or similar?

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Re: Latest PIOMAS update (September Interim)
« Reply #758 on: September 18, 2015, 11:40:15 AM »
Is using 1997 as the starting year for the linear fit supported by any method such as change point analysis or similar?

No, I did choose (in 2010) a subset to reduce the non-linearity below the noise and still having a reasonable number of points.
That is for the graph with the bunch of curve fits. The other graph with only a the linear fit is calculated over the full set.

Neven

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Re: Latest PIOMAS update (September Interim)
« Reply #759 on: September 18, 2015, 11:47:54 AM »
Subtracting the minimum from the maximum, it appears that 2015 had the third biggest annual volume decrease (after 2010 and 2012):

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AmbiValent

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Re: Latest PIOMAS update (September Interim)
« Reply #760 on: September 18, 2015, 12:14:14 PM »
Is there also a max-min comparison for max of spring and min of previous fall, to look at the effect of the refreeze season?
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Re: Latest PIOMAS update (September Interim)
« Reply #761 on: September 18, 2015, 12:20:13 PM »
Is there also a max-min comparison for max of spring and min of previous fall, to look at the effect of the refreeze season?

I'm sure there is something out there (probably on the Dosbat blog), but if no one posts anything, I'll try and make another bar graph later today.
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Jim Pettit

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Re: Latest PIOMAS update (September Interim)
« Reply #762 on: September 18, 2015, 01:15:36 PM »
Is there also a max-min comparison for max of spring and min of previous fall, to look at the effect of the refreeze season?

This isn't exactly what you're asking for, but it may be close. The red line shows the annual volume lost--that is, the difference between max and min. (IOW, it shows the same data that Neven's vertical bar graph does.) The blue line shows, obviously, annual volume maxima, and the grey columns indicate how much ice is left at minimum. That may seem a little backward, but I've shown in this way to better illustrate how, in the not too distant future, there'll likely be years where the blue and the red lines converge. That is, the grey columns will at some point vertically shrink to near zero.


Steven

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Re: Latest PIOMAS update (September Interim)
« Reply #763 on: September 18, 2015, 01:16:55 PM »
Is using 1997 as the starting year for the linear fit supported by any method such as change point analysis or similar?

No, I did choose (in 2010) a subset to reduce the non-linearity below the noise and still having a reasonable number of points.
That is for the graph with the bunch of curve fits. The other graph with only a the linear fit is calculated over the full set.

FWIW, the R software package called "segmented" (which can be used for change-point analysis) finds a change-point near 1996:

« Last Edit: September 18, 2015, 03:47:18 PM by Steven »

crandles

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Re: Latest PIOMAS update (September Interim)
« Reply #764 on: September 18, 2015, 01:29:13 PM »
an old one:

Piomas2.1meltfreeze by crandles57, on Flickr

seaicesailor

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Re: Latest PIOMAS update (September Interim)
« Reply #765 on: September 18, 2015, 01:43:48 PM »
Is there also a max-min comparison for max of spring and min of previous fall, to look at the effect of the refreeze season?

I'm sure there is something out there (probably on the Dosbat blog), but if no one posts anything, I'll try and make another bar graph later today.

Subtracting the minimum from the maximum, it appears that 2015 had the third biggest annual volume decrease (after 2010 and 2012):



Bad season for the Arctic ice, considering what could be called a "relatively cold" season and no Fram export.
Very simplistically, temperature ≠ heat.

seaicesailor

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Re: Latest PIOMAS update (September)
« Reply #766 on: September 18, 2015, 02:02:11 PM »
Quote
Given all this I don't expect August to see a loss of much over 2500 km3, unless PIOMAS has some melting momentum factor from July that bleeds through into August.

2629 km3 it is. Interesting...  :)

It looks like the dip in the anomaly trace came about 23rd-26th August, which would implicate the cyclone (and subsequent accelerated bottom melt) in the larger-than-expected volume decline.

Accelerated bottom melt means PIOMAS has some melting momentum factor from August that bleeds through into September.

Sunlight goes into the sea heating up the near surface layer during the early part of the season and this mixes upwards to melt ice later in the season. August cyclones can bring it up faster (notably in 2012) and result in melting happening earlier than it otherwise would. On the other hand if the Beaufort Gyre is in full swing, it takes a significant amount of this heat downwards resulting in rather less melting.

I agree. However the first 10 days of September, ocean SST anomalies were significant (+1C) at Beaufort and Chukchi sea. Browse SST anomaly maps thru these days here,

http://ocean.dmi.dk/arctic/satellite/index.uk.php

If you browse the Bremen maps until the 10th, you can see some ice melting from Beaufort and Chukchi, especially close to CAA, and the remainders at Chukchi).
The new buoy at CAB (81N), showed bottom melting until the 15th, now flat.

Refreezing starts. Clockwise drift due to prevailing high pressure over Beaufort too*. But I wouldn't be surprised ice front advances slowly during the next weeks.

*Is this drift called Beaufort Gyre too? I had recently learned the Beaufort Gyre is the slower ocean current beneath of much greater inertia, which does not stop flowing clockwise during the whole year, but only strengthens in intensity in Winter due to the mentioned prevailing Winter ice drift.


Neven

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Re: Latest PIOMAS update (September Interim)
« Reply #767 on: September 18, 2015, 02:53:28 PM »
Is there also a max-min comparison for max of spring and min of previous fall, to look at the effect of the refreeze season?

I'm sure there is something out there (probably on the Dosbat blog), but if no one posts anything, I'll try and make another bar graph later today.

Here it is, the maximum with the minimum of the previous year subtracted:

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crandles

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Re: Latest PIOMAS update (September Interim)
« Reply #768 on: September 18, 2015, 03:11:05 PM »
Piomasmaxminmeltfreeze by crandles57, on Flickr

Includes Sept 2015 estimated at 5.8 K Km^3. (31/8/15 was 5.975 and 15/9/15 5.713 so 5.8 probably isn't far out.)

AmbiValent

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Re: Latest PIOMAS update (September Interim)
« Reply #769 on: September 18, 2015, 03:14:12 PM »
Thanks a lot!
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Re: Latest PIOMAS update (September Interim)
« Reply #770 on: September 18, 2015, 06:00:31 PM »
Is there also a max-min comparison for max of spring and min of previous fall, to look at the effect of the refreeze season?

This isn't exactly what you're asking for, but it may be close. The red line shows the annual volume lost--that is, the difference between max and min. (IOW, it shows the same data that Neven's vertical bar graph does.) The blue line shows, obviously, annual volume maxima, and the grey columns indicate how much ice is left at minimum. That may seem a little backward, but I've shown in this way to better illustrate how, in the not too distant future, there'll likely be years where the blue and the red lines converge. That is, the grey columns will at some point vertically shrink to near zero.



Thank you, Jim.  I love this graph - it (and your previous versions) brilliantly illustrates how the system is changing.


For completeness here are the exponential and gompertz fits.
Very nice, and thank you Wipneus.

I am struck not so much by the trend, as I am the increasing volatility of the scalar measurements.  It seems to me to be evidence of a system about to undergo a major transition in behavior.

Worth noting - we are back to well below 2007 end-of-season volume.
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oren

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Re: Latest PIOMAS update (September Interim)
« Reply #771 on: September 20, 2015, 04:43:57 PM »
So looking at all these graps it seems 2015 was 3rd highest volume loss. Am I correct?

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Re: Latest PIOMAS update (September Interim)
« Reply #772 on: September 20, 2015, 11:54:36 PM »
Ice volume volatility due to the lack of MYI...Until a reasonable amount of the ice pack is MYI then this is going to happen year in and year out...huge fluctuations between years due to weather. Everyone is calling for a death spiral to the ice pack and to that I say hold on a second. While it is true that the downward progression was linear here is a counter argument to play Devil's advocate so to speak. The AMO had been in a warm cycle since 1995- until probably 2012 the evidence I present to you is the Atlantic hurricane season most of them in that time period had been extremely active. Now it appears we have gone into a quiet period which is normal when the AMO switches to cold it explains why the Northern Atlantic is suddenly cooler than normal and the shift in the Gulf Stream to the south...My theory is that the ice will rebound again because of this shift. It is the Atlantic Ocean that has the most exposure to the Arctic..anyway if there's no gain by 2020 I will fall in line with you

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Re: Latest PIOMAS update (September Interim)
« Reply #773 on: September 21, 2015, 09:01:46 AM »
Ice volume volatility due to the lack of MYI...Until a reasonable amount of the ice pack is MYI then this is going to happen year in and year out...huge fluctuations between years due to weather. Everyone is calling for a death spiral to the ice pack and to that I say hold on a second. While it is true that the downward progression was linear here is a counter argument to play Devil's advocate so to speak. The AMO had been in a warm cycle since 1995- until probably 2012 the evidence I present to you is the Atlantic hurricane season most of them in that time period had been extremely active. Now it appears we have gone into a quiet period which is normal when the AMO switches to cold it explains why the Northern Atlantic is suddenly cooler than normal and the shift in the Gulf Stream to the south...My theory is that the ice will rebound again because of this shift. It is the Atlantic Ocean that has the most exposure to the Arctic..anyway if there's no gain by 2020 I will fall in line with you

I agree this could be playing a role in years to come, but what does 'switching to cold' mean? How cold is it compared to previous times? And is it just the SSTs, or also the layers just below it? I'd like to know more about it in terms of ocean heat flux and atmospheric effects, but I guess there isn't much known about it because it's so hard to quantify.
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jai mitchell

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Re: Latest PIOMAS update (September Interim)
« Reply #774 on: September 24, 2015, 05:15:54 PM »
North Atlantic SST anomalies are a product of Greenland surface melt and a resulting decline in the AMOC.  The abnormally quiet current hurricane season (in the atlantic, not the pacific) is a result of significantly increased high altitude wind-shear and dry air off of the coast of africa.  These negative drivers for hurricane formation are well represented in the models, most of which predict a decline in the number of hurricanes in the atlantic basin as the earth warms, however these same models predict that rising mid-atlantic sea surface temperatures resulting from an increase in the Atlantic Gyre current and the availability of increased water vapor will produce much stronger hurricanes with landfall at further north latitudes when the regional circumstances become favorable for hurricane formation.

locked in warming and the reduction of aerosols will continue to increase the rates of sea ice loss in the near-term. 
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Wipneus

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Re: Latest PIOMAS update (October)
« Reply #775 on: October 05, 2015, 06:19:07 PM »
PSC has updated their PIOMAS  daily volume data. I updated my graphics, see the top post

Monthly gridded thickness data also updated (but not the daily), I will post the graphics tomorrow.

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Re: Latest PIOMAS update (September Interim)
« Reply #776 on: October 14, 2015, 01:09:01 PM »
iuote author=jai mitchell link=topic=119.msg63907#msg63907 date=1443107754]
North Atlantic SST anomalies are a product of Greenland surface melt and a resulting decline in the AMOC.  The abnormally quiet current hurricane season (in the atlantic, not the pacific) is a result of significantly increased high altitude wind-shear and dry air off of the coast of africa.  These negative drivers for hurricane formation are well represented in the models, most of which predict a decline in the number of hurricanes in the atlantic basin as the earth warms, however these same models predict that rising mid-atlantic sea surface temperatures resulting from an increase in the Atlantic Gyre current and the availability of increased water vapor will produce much stronger hurricanes with landfall at further north latitudes when the regional circumstances become favorable for hurricane formation.

locked in warming and the reduction of aerosols will continue to increase the rates of sea ice loss in the near-term.
[/quote]

What would account then for the longest landfalling hurricane drought in US history then? It's been quite a few years now of less activity not just this El Niño mess and the closest thing I can find that explains most of what we have been seeing in the Atlantic and Arctic is the AMO.Judith Curry has done a lot of compelling research on this very topic but I agree with Neven much more needs to be done.

Wipneus

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Re: Latest PIOMAS update (October)
« Reply #777 on: October 24, 2015, 02:53:03 PM »
Average monthly thickness of September 2015 compared with years 2006-2014.
PIOMAS still shows 3+ m thick ice between the Canadian Archipelago and the pole, where Cryosat 2 and Jaxa thickness maps do not.

Click on the images for bigger pictures.

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Re: Latest PIOMAS update (November)
« Reply #778 on: November 05, 2015, 09:28:45 AM »
PSC has updated their PIOMAS  daily volume data. I updated my graphics, see the top post

Monthly gridded thickness data also updated , I will post those graphics later.

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Re: Latest PIOMAS update (November)
« Reply #779 on: November 05, 2015, 10:08:09 AM »
Average monthly thickness of October 2015 compared with years 2006-2014.
PIOMAS still shows 3+ m thick ice between the Canadian Archipelago and the pole, where Cryosat 2 thickness maps do not. Cryosat 2 and Jaxa thickness maps show a blob of thicker ice between Svalbard and the pole, that can not be seen in the PIOMAS map.

Click on the images for bigger pictures.

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Re: Latest PIOMAS update (November)
« Reply #780 on: November 05, 2015, 10:30:37 AM »
From the daily gridded thickness data an animation of the ice thickness during September and October.

Click to start.

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Re: Latest PIOMAS update (November)
« Reply #781 on: November 05, 2015, 10:35:08 AM »
bears quite little resemblance to the measurement:
http://www.cpom.ucl.ac.uk/csopr/seaice.html

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Re: Latest PIOMAS update (November)
« Reply #782 on: November 05, 2015, 11:44:16 AM »
Thanks, Wipneus. I'll add your graph to the PIOMAS update over on the ASIB.
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Re: Latest PIOMAS update (November)
« Reply #783 on: November 06, 2015, 10:34:08 PM »
Considering how low extent went I'm pleased with volume numbers this month. Notice that the last few years have actually been staggered gains against the linear line on Neven's ASIB graph. It was a couple standard deviations below the linear line before 2013...I think the trend upward is just being slightly delayed this year by El Niño and we will see another spike up higher than the previous years in either 2016 or maybe 2017 when the ocean loses some of that heat energy built up on the Pacific side. This also means global temperatures will drop off too...maybe as much as 0.5C given the strength of this event. A La Niña working with a cold AMO would greatly affect ice for the positive...However if 2015 is just a new plateau point for global temperatures then it is a continuation of the death spiral. Interesting times ahead many questions are about to be answered one way or another

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Re: Latest PIOMAS update (November)
« Reply #784 on: November 08, 2015, 01:13:51 PM »
Considering how low extent went I'm pleased with volume numbers this month. Notice that the last few years have actually been staggered gains against the linear line on Neven's ASIB graph. It was a couple standard deviations below the linear line before 2013...I think the trend upward is just being slightly delayed this year by El Niño and we will see another spike up higher than the previous years in either 2016 or maybe 2017 when the ocean loses some of that heat energy built up on the Pacific side. This also means global temperatures will drop off too...maybe as much as 0.5C given the strength of this event. A La Niña working with a cold AMO would greatly affect ice for the positive...However if 2015 is just a new plateau point for global temperatures then it is a continuation of the death spiral. Interesting times ahead many questions are about to be answered one way or another
KB ,
There are a couple of  minor problems with this analysis.

The first issue is that the heat from an El Nino appears to  take a year to get to the Arctic so the big declines do not  occur until the year after the El Nino, you can see this if you  check out the declines in extent  after the 1983, 1998 El Ninos. Both 1984 and 1999  saw big drops in extent.

The second issue is that this El Nino will be the 2016 El Nino not the 2015 El Nino. They are usually known by the year they peak and break. The heat stays around for most of that year . This El Nino is still building and will result in both 2015 and 2016 being record breaking warm years.

There is very  little hope of a rise in sea ice extent or volume over the next two years and I  expect that by the end of 2017 the record minimum extent will start with a 2 not a 3.

Its also worth noting that temperatures have not dropped more than 0.3 degrees after a record warm year for decades. After 1998 only two years were cooler than the previous record hottest year, and the decline was less than 0.25 degrees. I  don't expect we will see a year as cool as 2014 in our lifetimes.

 
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seaicesailor

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Re: Latest PIOMAS update (November)
« Reply #785 on: November 08, 2015, 02:04:10 PM »
bears quite little resemblance to the measurement:
http://www.cpom.ucl.ac.uk/csopr/seaice.html


The latest NSIDC News and Analysis has interesting remarks about the differences between Cryosat and other ice thickness sources like PIOMAS and SMOS measurements. Also it explains that SMOS thicknesses above 1m must not be trusted.

http://nsidc.org/arcticseaicenews/

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Re: Latest PIOMAS update (November)
« Reply #786 on: December 05, 2015, 12:22:33 AM »
PIOMAS has been updated. I'll have a post up on the ASIB somewhere tomorrow.

In the meantime, The Cryosphere has this:

Quote
Improved Arctic sea ice thickness projections using bias-corrected CMIP5 simulations
N. Melia1, K. Haines2, and E. Hawkins3

Abstract. Projections of Arctic sea ice thickness (SIT) have the potential to inform stakeholders about accessibility to the region, but are currently rather uncertain. The latest suite of CMIP5 global climate models (GCMs) produce a wide range of simulated SIT in the historical period (1979–2014) and exhibit various biases when compared with the Pan-Arctic Ice–Ocean Modelling and Assimilation System (PIOMAS) sea ice reanalysis. We present a new method to constrain such GCM simulations of SIT via a statistical bias correction technique. The bias correction successfully constrains the spatial SIT distribution and temporal variability in the CMIP5 projections whilst retaining the climatic fluctuations from individual ensemble members. The bias correction acts to reduce the spread in projections of SIT and reveals the significant contributions of climate internal variability in the first half of the century and of scenario uncertainty from the mid-century onwards. The projected date of ice-free conditions in the Arctic under the RCP8.5 high emission scenario occurs in the 2050s, which is a decade earlier than without the bias correction, with potentially significant implications for stakeholders in the Arctic such as the shipping industry. The bias correction methodology developed could be similarly applied to other variables to reduce spread in climate projections more generally.
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Re: Latest PIOMAS update (December)
« Reply #787 on: December 05, 2015, 08:13:37 AM »
Indeed, PSC has updated their PIOMAS  daily volume data. I updated my graphics, see the top post

Gridded data was updated as well. Update of those graphics probably tomorrow.

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Re: Latest PIOMAS update (December)
« Reply #788 on: December 06, 2015, 10:45:38 AM »
Average monthly thickness of November 2015 compared with years 2006-2014.
There is still an area of anomalous thick ice between Ellesmere and pole.

Click on the images for bigger pictures.

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Re: Latest PIOMAS update (December)
« Reply #789 on: December 06, 2015, 11:02:32 AM »
And an animation of the thickness map during November 2015. Click to start.

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Re: Latest PIOMAS update (December)
« Reply #790 on: December 06, 2015, 02:41:11 PM »
Thanks for the collage, Wip!
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Re: Latest PIOMAS update (December)
« Reply #791 on: December 08, 2015, 12:24:16 PM »
Post is up over on the ASIB now.
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Re: Latest PIOMAS update (December)
« Reply #792 on: December 08, 2015, 02:36:25 PM »
Here is a 700 ms animation of inter-year comparisons to November 2015. Done from #788 using guilllotine in gimp, save as, open as layers, rescale to 700 pxl width. It could be done at even larger forum scale by moving legend over and recropping but this seems to overshoot the intrinsic resolution.
« Last Edit: December 08, 2015, 03:05:00 PM by A-Team »

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Re: Latest PIOMAS update (January)
« Reply #793 on: January 06, 2016, 08:39:41 AM »
PSC has updated their PIOMAS  daily volume data. I updated my graphics, see the top post

Gridded thickness data also updated, I will post the graphics later.

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Re: Latest PIOMAS update (January)
« Reply #794 on: January 06, 2016, 10:02:07 AM »
Average monthly thickness of December 2015 compared with years 2006-2014.
There is still an area of anomalous thick ice between Ellesmere and pole.

Click on the images for bigger pictures.

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Re: Latest PIOMAS update (January)
« Reply #795 on: January 06, 2016, 10:27:22 AM »
And here an animation of the daily ice thickness development during December.

click to animate.

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Re: Latest PIOMAS update (January)
« Reply #796 on: January 06, 2016, 12:23:26 PM »
Thanks, Wipneus. I'm waiting for the PSC to update their graphs, and then I'll put up a blog post.
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Re: Latest PIOMAS update (January)
« Reply #797 on: January 06, 2016, 12:46:53 PM »
As far as I see, they did :




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Re: Latest PIOMAS update (February)
« Reply #798 on: February 04, 2016, 08:54:32 AM »
Still waiting for the regular PIOMAS volume data update. Should not be long as the gridded thickness data just appeared. Graphs will appear asap, lots of 2015->2016 changes to be made.

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Re: Latest PIOMAS update (February)
« Reply #799 on: February 04, 2016, 10:21:27 AM »
Average monthly thickness of January 2016 compared with years 2007-2015.

Click on the images for bigger pictures.