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Author Topic: Latest PIOMAS update (June)  (Read 452005 times)

Wipneus

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Re: Latest PIOMAS update (September)
« Reply #100 on: September 06, 2013, 06:43:12 PM »
Updated, graphs are in the top post.

dlen

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Re: Latest PIOMAS update (September)
« Reply #101 on: October 08, 2013, 02:25:26 AM »
Remark to the yearly min-to-max volume gains:

The amplidude of the ice thickness oscillation is to be expected to increase considerably with decreasing mean thickness, because the winter heat flux is much higher with thin ice. And the ice growth rate depends directly on the heat flux going up into the atmosphere.
But this holds strictly only for areas with no summer melt-out.
In areas with summer melt-out, the thickness oscillation amplitude depends mostly on the iceless time, decreasing with it more and more.
So with the ice becoming thinner, the increasing thickness oscillation in areas with no melt-out and the decreasing thickness oscillation in areas with summer melt-out add up to a volume oscillation amplitude, which increases a little bit, until the summer melt-out becomes too large, then it decreases again.






Wipneus

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Re: Latest PIOMAS update (October)
« Reply #102 on: November 05, 2013, 08:05:41 AM »
Updated, monthly graphs are in the top post.

The minimum 2013 value was 4.942 [1000 km3] at September 7.

Yearly minimum fit to exponential trend:



Yearly minimum fit to linear trend:



Yearly minimum fit to Gomperts trend:





jdallen

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Re: Latest PIOMAS update (October)
« Reply #103 on: November 05, 2013, 09:13:37 AM »
Thank you Wipneus - marvelous work as typical.

I'd say we are still on track for "ice free" sometime between now and 2020.  Perhaps not by my low end guess (2017), but close.
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idunno

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Re: Latest PIOMAS update (October)
« Reply #104 on: November 05, 2013, 12:23:09 PM »
Hi Wipneus,

One of us is confused.

AFAICT, PIOMAS has just updated for the figures for September, and October is yet to be released.

Wipneus

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Re: Latest PIOMAS update (October)
« Reply #105 on: November 05, 2013, 01:29:39 PM »
Hi Wipneus,

One of us is confused.

AFAICT, PIOMAS has just updated for the figures for September, and October is yet to be released.

Actually I am confused as well. The explanation is this: the monthly update for any month has data normally updated to the last date of the previous month. I am following Neven's standard in the blog here. That last day of the last month can also be regarded as day zero of this month, so at least it makes some sense (to someone at least).

Now hopefully we get the data for October very soon right up to the zeroth of November, so I will call it that the November update and we can forget this confusing episode  ;)

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Re: Latest PIOMAS update (November)
« Reply #106 on: November 16, 2013, 07:43:56 AM »
Updated, graphs are in the top post.

ChrisReynolds

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Re: Latest PIOMAS update (November)
« Reply #107 on: November 16, 2013, 08:04:49 AM »
Thanks Wipneus.

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Re: Latest PIOMAS update (November)
« Reply #108 on: November 16, 2013, 08:42:07 AM »
Updated, graphs are in the top post.

Wipneus, I'm not trying to go off subject, but when I click on your links, it's the same certificate error message I once had logging onto this site with https. I easily changed mine to http by staying logged in and switching sites.

This isn't a complaint and just a possible suggestion that may lead to a solution for some people's problems. You may have your reasons for sticking to https, like I did using a proxy server in the past. I think the problem can be solved by registering the security certificate to both website addresses, but I don't know for sure, because I've never been there and done that.

When I click your links, I'm switched to the https site that doesn't have a security certificate.

Does any of that make sense?

 

Wipneus

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Re: Latest PIOMAS update (November)
« Reply #109 on: November 17, 2013, 08:03:22 AM »

You may have your reasons for sticking to https, like I did using a proxy server in the past. I think the problem can be solved by registering the security certificate to both website addresses, but I don't know for sure, because I've never been there and done that.


Well, I am using https because the proprietor and the web master (know as user DungeonMaster) asked me to.

I might be wrong, but the web certificate seems to be a matter of costs. No idea how much, but I'd be happy to make a contribution if that is the case.

ChrisReynolds

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Re: Latest PIOMAS update (November)
« Reply #110 on: November 25, 2013, 09:55:04 PM »
Regional PIOMAS volume breakdown available as a csv file here:
https://drive.google.com/file/d/0B3pB-kdzoLU3WXpaMWtUTnFJalE/edit?usp=sharing

A set of volume/thickness breakdowns will be calculated, but due to my day job probably not until the weekend.

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Re: Latest PIOMAS update (November)
« Reply #111 on: November 26, 2013, 08:53:02 PM »
For completeness,

PIOMAS thickness broken down into regions.
https://drive.google.com/file/d/0B3pB-kdzoLU3RkU4WUZuLXVxeGM/edit?usp=sharing

PIOMAS volume and thickness broken into regions for Excel 2007 and later. Contains user selectable tables breaking down into region and month. Contains VBA code used to process in 'module 2' of the VBA tree.
https://drive.google.com/file/d/0B3pB-kdzoLU3NlhLSno2aVk0Q0U/edit?usp=sharing

Wipneus

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Re: Latest PIOMAS update (December)
« Reply #112 on: December 04, 2013, 08:06:17 AM »
Updated, graphs are in the top post.

Interesting, the "pause" in the extent increase beginning of November is reflected in the volume increase as well.

ChrisReynolds

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Re: Latest PIOMAS update (December)
« Reply #113 on: December 06, 2013, 05:54:01 PM »
Wipneus,

I've been working again on grid areas for PIOMAS for the last few days. Your calculation (if you remember) was

(HTN+HUS)/2 * (HTE+HUW)/2

Which gives the closest to the main PIOMAS series you can get with the data in grid.dat.pop.

I've not been able to improve on that so have contacted Dr Zhang. It turns out that HUS and HUW are vector quantities, so instead of using those figure from grid.dat.pop we should have calculated by obtaining the other edges (HUS and HUW) from adjacent grid cells. That's the method Dr Zhang uses.

So with an array Grid(1 to 120, 1 to 360,XXX), where XXX is for example HTN or HTE the grid cell area is calculated as:

(Grid(n,m,HTN)+Grid(n-1,m,HTN))/2 * (Grid(n,m,HTE)+Grid(n,m-1,HTE))/2

Using this the error drops to about 0.01%, including the landmask in calculations drops the error far lower (can't remember the figure but it's orders of magnitude - Excel tied up right now checking results).

I'll post on my blog and include a link to the revised grid cell area mask in the next couple of days. But I'm going to try to remove some more of the error first.

Wipneus

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Re: Latest PIOMAS update (December)
« Reply #114 on: December 06, 2013, 07:05:00 PM »
... we should have calculated by obtaining the other edges (HUS and HUW) from adjacent grid cells. That's the method Dr Zhang uses.

So with an array Grid(1 to 120, 1 to 360,XXX), where XXX is for example HTN or HTE the grid cell area is calculated as:

(Grid(n,m,HTN)+Grid(n-1,m,HTN))/2 * (Grid(n,m,HTE)+Grid(n,m-1,HTE))/2


Great, although the differences are small it was not nice not to know the reason why.

Thanks.


ChrisReynolds

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Re: Latest PIOMAS update (December)
« Reply #115 on: December 06, 2013, 07:09:54 PM »
My attitude had been that -0.6% was acceptable in view of PIOMAS uncertainties.

But to get it so much closer is so much better.  ;D

Wipneus

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Re: Latest PIOMAS update (December)
« Reply #116 on: December 22, 2013, 08:15:24 AM »
Gridded thickness data was updated until November 2013 as well.

Attached are thickness differences with 2012, to compare with Cryosat-2.

Wipneus

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Re: Latest PIOMAS update (December)
« Reply #117 on: December 22, 2013, 09:50:59 AM »
Here are the thickness maps for October and November:


Neven

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Re: Latest PIOMAS update (December)
« Reply #118 on: December 22, 2013, 10:11:21 AM »
Nice work, as always, Wipneus.
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crandles

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Re: Latest PIOMAS update (December)
« Reply #119 on: December 22, 2013, 01:55:21 PM »
Very interesting Wipneus, thank you.

My view /summary:

Red area by Ellesmere island won't melt out in 2014 anyway. There are large areas - Beaufort round to East Siberian and Central Arctic where thickness already seems to be regressing back to 2012 thicknesses.

There is a build up of extra thickness in Barents - this is probably what would be anticipated looking at extent and area products. Bering isn't covered but there is clearly less ice there from area and extent products. It would be unusual if there wasn't a case of a bit more on one side and a little less on another side.

While that summary sound much like all very much as expected, it is interesting to see. It seems quite early for to me for such large areas to already be showing such marked regression towards 2012 thicknesses.

Maybe other people see different things or have different opinions?

Nice to have it so up to date. :)

ChrisReynolds

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Re: Latest PIOMAS update (December)
« Reply #120 on: December 22, 2013, 02:16:09 PM »
Thanks Wipneus,

You ended up beating me to it anyway. Here's my blog post on the data:
http://dosbat.blogspot.co.uk/2013/12/new-piomas-gridded-data-november-2013.html

Wipneus

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Re: Latest PIOMAS update (December)
« Reply #121 on: January 05, 2014, 02:08:57 PM »
The PIOMAS daily update is not in yet, but for the first time the gridded monthly data has come first!

The difference between 2013 and 2012 is slowly getting less (September-December 2013 vs 2012):

1661  1937  1865  1689 km3

Attached are maps of thickness in Dec 2012 and Dec 2013, and the differences.

crandles

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Re: Latest PIOMAS update (December)
« Reply #122 on: January 05, 2014, 03:07:22 PM »
Thanks Wipneus, that is great.

Is a difference map between the November differences and the December differences difficult to produce?


Wipneus

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Re: Latest PIOMAS update (December)
« Reply #123 on: January 05, 2014, 05:27:21 PM »
Thanks Wipneus, that is great.

Is a difference map between the November differences and the December differences difficult to produce?

No it is not difficult to produce.

You ask for the following:

(thickness.dec.2013 - thickness.dec.2012) -(thickness.nov.2013 - thickness.nov.2012)

but this is the same as

(thickness.dec.2013 - thickness.nov.2013) -(thickness.dec.2012 - thickness.nov.2012)

Which I prefer to call difference of nov-dec growth.

Attached.

crandles

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Re: Latest PIOMAS update (December)
« Reply #124 on: January 05, 2014, 08:12:33 PM »
Thanks Wipneus :)

So more mechanical thickening by Greenland and Canada. Elsewhere over large areas there is less growth and this seems pretty much regardless of whether ice was thicker or thinner than last year. In Kara and Barents there is thicker ice which is thickening faster but thicker ice seems an unlikely cause for this.

If relative ice thickness does not seem to be a major driver, what is/are?

Warmer weather this year than last? More snow insulation? Higher upward heat flux? Less area of leads preventing heat escaping easily? Other factors?

« Last Edit: January 05, 2014, 08:18:16 PM by crandles »

jdallen

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Re: Latest PIOMAS update (December)
« Reply #125 on: January 05, 2014, 08:49:20 PM »
Thanks Wipneus :)

So more mechanical thickening by Greenland and Canada. Elsewhere over large areas there is less growth and this seems pretty much regardless of whether ice was thicker or thinner than last year. In Kara and Barents there is thicker ice which is thickening faster but thicker ice seems an unlikely cause for this.

If relative ice thickness does not seem to be a major driver, what is/are?

Warmer weather this year than last? More snow insulation? Higher upward heat flux? Less area of leads preventing heat escaping easily? Other factors?

A number of the buoys are reporting significant snow cover - as much as a meter.  This would retard thickening.
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Wipneus

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Re: Latest PIOMAS update (January)
« Reply #126 on: January 07, 2014, 07:35:01 AM »
Updated, graphs are in the top post.
« Last Edit: January 07, 2014, 08:14:10 AM by Wipneus »

Jim Pettit

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Re: Latest PIOMAS update (January)
« Reply #127 on: January 07, 2014, 05:11:40 PM »
Thanks, Wipneus. FWIW, I've updated my SIV graphs with the December PIOMAS figures:

https://sites.google.com/site/pettitclimategraphs/pettit-climate-graphs

(3D volume graphs can be found here.)

Buddy

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Re: Latest PIOMAS update (January)
« Reply #128 on: January 07, 2014, 06:26:30 PM »
This is NOT setting up to a good year for the Arctic.  Things can change.....but this does NOT look good.
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werther

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Re: Latest PIOMAS update (January)
« Reply #129 on: January 07, 2014, 08:33:22 PM »
Hi Buddy,
I felt "not good" on climate change/AGW for years. And very worried last winter.

But some parameters give me at least some spare time to see if the situation for this year will indeed be "NOT GOOD".
Now that PIOMAS December is in, it is clear that volume is not rejoining the '10-'12 trend for some time. Reynolds suggested that part of the conserved/not molten CAB volume may stack into a higher portion of MYI at the start of this melt-season.

That doesn't mean the outcome of a brutal summer will be less than dramatic. We'll see. If the weird circulation goes on, teams up with a new El Nino and so on, NOT GOOD will be an understatement.

Buddy

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Re: Latest PIOMAS update (January)
« Reply #130 on: January 07, 2014, 09:06:26 PM »
My biggest concern (other than a lack of intelligence in the US Congress:) is the "seemingly" growing number of heat anomalies in the sea surface temperatures.  More "warm anomalies" have been popping up over the past couple of months.  And of course.....the area off of southern Greenland is warmer than usual. 

http://climatechangegraphs.blogspot.com/2013/02/sea-surface-temperature-anomaly-weekly.html

As well.....the western US is dry....dry....dry.  Climate.....as I have found out over the last 5 years....is one tricky puzzle, with a lot of interacting parts.  But as you folks all know too well.....the number of parts that are looking worse and worse over time........is growing.  Not only growing, but literally growing right in front of our eyes.  NOT GOOD....

The Arctic and Greenland are just two of the bigger canaries in the proverbial coal mine.   If the ice sheet level in the Arctic continues its near/at record level into the beginning of melt season in April.....it will not be a pretty thing.

       
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jdallen

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Re: Latest PIOMAS update (January)
« Reply #131 on: January 07, 2014, 09:16:31 PM »
@Buddy - you are echoing me last year at this time.  However, to the surprise of us all, the ice did not crash.  The crucial period appears to be early to mid spring.

That notwithstanding, the anomalous weather events are multiplying.  Change is happening.  It will not be prompt, nor consistent, even with a "melt out".  That will just be another signal, if a dramatic one, but far less ominous than the changes to weather patterns in the mid latitudes which have already started.
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deep octopus

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Re: Latest PIOMAS update (January)
« Reply #132 on: January 07, 2014, 10:15:54 PM »
The below-average snow coverage in Europe is on watch for me. This is compounded by models which project a very warm late winter/early spring for Europe and western Siberia.
https://lh5.googleusercontent.com/-VUmsaYV62iY/Usxq7rUl7WI/AAAAAAAAAPc/-YmmcZD1bH4/w1018-h787-no/glbT2mSeaInd1.gif

If snow melt gets ramped up early and quickly, I suppose the sea ice could get a rude awakening by April. However, like jdallen, in March of last year, it appeared to me that what looked like a rapid ice loss event in the making was was soon stymied by unexpected changes in weather patterns. But we do have some interesting circumstances taking shape (the snow/early spring situation being one.)

ritter

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Re: Latest PIOMAS update (January)
« Reply #133 on: January 08, 2014, 05:23:39 PM »
@Buddy - you are echoing me last year at this time.  However, to the surprise of us all, the ice did not crash.  The crucial period appears to be early to mid spring.

Well, not in the summer at least. It's waited until December/January to get to new lows.....  :o

Wipneus

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Re: Latest PIOMAS update (January)
« Reply #134 on: February 05, 2014, 11:21:42 AM »
PIOMAS gridded thickness data has been updated, again ahead of the official non-gridded data.

My estimate for January 2014 is 17.300 km3 which brings it at the 4th lowest place, just below 2010 but above 2011, 2012 and 2013.

Preparing some maps...

Wipneus

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Re: Latest PIOMAS update (January)
« Reply #135 on: February 05, 2014, 11:30:20 AM »
Here are thickness maps for January 2013 and 2014, and a map of the differences between them.

KielFish

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Re: Latest PIOMAS update (January)
« Reply #136 on: February 05, 2014, 11:42:11 AM »
Hi Wipneus,

Thanks for making those maps. I would like to play around with the data myself but I have a bit of confusion over the datasets. Whilst attempting to get the gridded PIOMAS data (from here: ftp://psc.apl.washington.edu/zhang/IDAO/retrospection/) I found two files: heff.H2013.gz and heff.txt2013.gz (using 2013 as an example). Am I correct to assume that these are the same datasets? In which case, the text file seems much more user-friendly - despite my best efforts I cannot understand the data structure of the first file.

Wipneus

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Re: Latest PIOMAS update (January)
« Reply #137 on: February 05, 2014, 11:44:00 AM »
And the difference between the growth from December to January and  the growth last year.
« Last Edit: February 05, 2014, 12:32:49 PM by Wipneus »

Wipneus

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Re: Latest PIOMAS update (January)
« Reply #138 on: February 05, 2014, 12:05:13 PM »
Hi Wipneus,

Thanks for making those maps. I would like to play around with the data myself but I have a bit of confusion over the datasets. Whilst attempting to get the gridded PIOMAS data (from here: ftp://psc.apl.washington.edu/zhang/IDAO/retrospection/) I found two files: heff.H2013.gz and heff.txt2013.gz (using 2013 as an example). Am I correct to assume that these are the same datasets? In which case, the text file seems much more user-friendly - despite my best efforts I cannot understand the data structure of the first file.

Yes they should be the same. Yet the resolution is one centimeter, the binary files could be more accurate. Also the 2014 data seems to be available only as a binary.

As documentation the read_hi_uice.f is to be used, if that helps.

My programs are written in R, if you could use that let me know. Another frequenter here, Chris Reynolds does everything in Excel he may be able to help as well.

werther

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Re: Latest PIOMAS update (January)
« Reply #139 on: February 05, 2014, 12:15:52 PM »
And the difference between the growth from December to January and  the growth last year.

Those two graphs look the same, Wipneus... it's not immediately clear to me what to make of them...

Wipneus

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Re: Latest PIOMAS update (January)
« Reply #140 on: February 05, 2014, 12:37:43 PM »
Something went a bit wrong:
The first time I pressed "Post", I got a warning from another post. Then I pressed "Post" again, at that time the attachment was gone. So I attached again  and now I have two attachments.

There should be only one image now, thanks for noticing.

KielFish

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Re: Latest PIOMAS update (January)
« Reply #141 on: February 05, 2014, 03:16:50 PM »
Thanks for the clarification Wipneus, I think I can use my own tools to process the data from the text files for now. I do a bit of web development and would like to make some interactive thickness maps using the PIOMAS data. I have some good ideas on how it may work but needed to get the data into a suitable format first - the first stumbling block of many I'm sure. Will keep you updated if anything comes of it.

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Re: Latest PIOMAS update (January)
« Reply #142 on: February 05, 2014, 07:30:58 PM »
Kielfish,

You'll find metadata extracted from the gridded data here at my blog.
http://dosbat.blogspot.co.uk/2013/12/regional-piomas-volume-data.html
There's volume broken down into regions, regional breakdown of a breakdown of volume contribution from various thickness bands (thickness of grid cell in a given month), and regional average thickness. Thickness doesn't exactly tally with the PIOMAS thickness series.

On that page you'll also find an explanation of how to calculate grid cells.

A correspondent of mine (email) has been having problems with the text files, for a start they don't contain enough elements to cover the entire PIOMAS domain. but as I use the binaries I can't advise further than that note of caution.

In case it's of use (i.e. you do decide to tackle the binaries) here is the Excel Visual Basic code core I use to populate arrays with gridded data, e.g. thickness .heff files, and a shadow array containing necessary overhead data for each grid point. If you need the binary files for grid cell area or region mask just ask, the lattitude and longitude are available here (you'll need scalar - grid.dat), which you already know about:
http://psc.apl.washington.edu/zhang/IDAO/data_piomas.html
(That's for other readers really)

'***************************Data Acquisition Functs/Subs******************************

Private Sub LoadData(DataArray() As Single, DataIndex As String, MonthIndex As Integer, YearIndex As Integer)

Dim n As Long
Dim Word As Single
Dim URLstring As String

Select Case DataIndex
   Case "Thick"
   FileID = "heff.h"
   FolderID = "Thickness\"
   MinYear = 1978
   MaxYear = 2013
   Case "Conc"
   FileID = "area.h"
   FolderID = "Concentration\"
   MinYear = 1978
   MaxYear = 2012
   Case "Grow"
   FileID = "icegrow.h"
   FolderID = "Growth Rate\"
   MinYear = 1978
   MaxYear = 2004
   Case "OFlux"
   FileID = "Oflux.h"
   FolderID = "Ocean Flux\"
   MinYear = 1978
   MaxYear = 2004
   Case Else
   Debug.Print "*****LoadData terminated - no such category***************"
   End
End Select

If YearIndex < MinYear Then
   Debug.Print "*****LoadData terminated - Invalid Year = "; YearIndex
   End
End If
If YearIndex > MaxYear Then
   Debug.Print "*****LoadData terminated - Invalid Year = "; YearIndex
   End
End If

'make the URL for the source file
URLstring = "C:\Users\Computer\Documents\PIOMAS\Data\" + FolderID + FileID + CStr(YearIndex)

'open the source file
Open URLstring For Binary Access Read As #1
   
'load DataArray from file - 43200 data points for each month, 12 months per file.
   For Lat = 1 To 120
     For Lon = 1 To 360
      Get #1, (Lat - 1) * 1440 + 1 + (Lon - 1) * 4 + (MonthIndex - 1) * 172800, Word
      DataArray(Lat, Lon) = Word
     Next Lon
   Next Lat

Close #1

Debug.Print "Source Data loaded OK ", Time()

End Sub




Private Sub LoadGridPoints(GridArray() As Single)
'GridArray is a 3d array, first 2 indices are grid number lat and lon as index, second is 1=longitude,
                          '1=latitude (actual lat and lon of grid box), 3=area, 4=region, 5=LandMask
                          'declare as Dim GridArray(1 To 120, 1 To 360, 1 To 5) As Single

Dim Word As Single
Dim InByte As Byte
Dim n As Long
Dim LandMaskString As String

Open "C:\Users\Computer\Documents\PIOMAS\Data\Lat.bin" For Binary Access Read As #1
Open "C:\Users\Computer\Documents\PIOMAS\Data\Lon.bin" For Binary Access Read As #2
Open "C:\Users\Computer\Documents\PIOMAS\Data\GridArea.bin" For Binary Access Read As #3
Open "C:\Users\Computer\Documents\PIOMAS\Data\Region.bin" For Binary Access Read As #4
Open "C:\Users\Computer\Documents\PIOMAS\Data\io.dat_360_120.output" For Input As #5

'Load Lat and Lon into strings

'Load Land mask into string
Input #5, LandMaskString

'Load Grid lat and lon and area.
For Lat = 1 To 120
 For Lon = 1 To 360
   'load longitude
     Get #1, , Word
     GridArray(Lat, Lon, 1) = Word
   'load latitude
     Get #2, , Word
     GridArray(Lat, Lon, 2) = Word
   'load area
     Get #3, , Word
     GridArray(Lat, Lon, 3) = Word
   'Load Region Code
     Get #4, , InByte
     GridArray(Lat, Lon, 4) = InByte
   'Load Land Mask, 1 = sea -1 = land
     If Mid(LandMaskString, (((Lat - 1) * 360 + Lon) * 2) - 1, 2) > 0 Then
      GridArray(Lat, Lon, 5) = 1
     Else
      GridArray(Lat, Lon, 5) = -1
     End If
  Next Lon
Next Lat

'close source files
Close #1
Close #2
Close #3
Close #4
Close #5

Debug.Print "Grid Data loaded OK ", Time()

End Sub

ChrisReynolds

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Re: Latest PIOMAS update (January)
« Reply #143 on: February 05, 2014, 07:35:33 PM »
Thanks Wipneus,

Guess I'd better do a blog post tonight...

Although I may just watch a film.  ;D

ChrisReynolds

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Re: Latest PIOMAS update (January)
« Reply #144 on: February 05, 2014, 11:06:54 PM »
Loads of graphs in my January post, for those who like such things.
http://dosbat.blogspot.co.uk/2014/02/piomas-january-2014.html

ChrisReynolds

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Re: Latest PIOMAS update (January)
« Reply #145 on: February 06, 2014, 08:10:24 AM »
There's been a change to the PIOMAS gridded data, I've not yet checkd the main daily series.

Graphs in the above blog post will be updated when I get back from work. The spring volume loss and 2010 volume loss remains. But the 2013 volume gain is less, and minimum volume for sept 2012 is greater.

Wipneus

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Re: Latest PIOMAS update (January)
« Reply #146 on: February 06, 2014, 08:29:32 AM »
Indeed, I had expected the official daily PIOMAS data would be available by now so I waited.

But:
Gridded data has changed substantially for 2009-2013;
For instance minimum 2012 is now about 3.76, was 3.37 [1000 km3];
max difference (June 2013) 1.43 [1000 km3];
all differences from 2010-2013 are positive: ice is thicker;

Will the change in gridded data also be seen in the non-gridded data? Is a new release (v3) to be announced?

We will have to wait a bit longer.

crandles

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Re: Latest PIOMAS update (January)
« Reply #147 on: February 06, 2014, 12:37:24 PM »
The 15 June 2011 new version (v2) section says

The long term trend is reduced to about -2.8 103 km3/decade from -3.6 km3 103/decade in the last version. Our comparisons with data and alternate model runs indicate that this new trend is a conservative estimate of the actual trend.  New with this version we provide uncertainty statistics. More details can be found in Schweiger et al. 2011.  Model improvement is an ongoing research activity at PSC and model upgrades may occur at irregular intervals.  When model upgrades occur, the entire time series will be reprocessed and posted.

Sounds like the trend is reduced again despite last trend being conservative. If the volume keeps being adjusted upwards and the trend reduced, then it allows more time for a long tail as shown by models to make an appearance.

Wipneus

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Re: Latest PIOMAS update (January)
« Reply #148 on: February 06, 2014, 12:59:20 PM »
A revision that only affects 2009-2010 sounds that some input data is revised. It cannot be Cryosat-2, if it would be all long term trends would be suspicious.

Here are the estimated differences (new - old) per month:

   ---2010 -----2011 ------2012 -------2013
jan 130.9539 226.3197  597.5953  627.5944
feb 389.9285 329.3752  761.9594  846.4948
mar 553.0858 426.7384  971.5580  965.6704
apr 711.5166 589.9611 1251.2395 1299.9121
may 849.3467 786.4040 1414.8699 1431.0550
jun 617.8464 654.0335 1102.3938 1113.6824
jul 429.6737 485.5981  796.5020  755.9716
aug 224.9569 355.0028  528.3009  530.1337
sep 130.9260 242.2494  387.0746  403.8874
oct 101.2592 185.9627  337.7706  335.4152
nov 125.9876 212.0406  338.1416  313.2785
dec 220.8414 403.0042  455.7761  397.5223

jdallen

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Re: Latest PIOMAS update (January)
« Reply #149 on: February 06, 2014, 06:28:26 PM »
The 15 June 2011 new version (v2) section says

The long term trend is reduced to about -2.8 103 km3/decade from -3.6 km3 103/decade in the last version. Our comparisons with data and alternate model runs indicate that this new trend is a conservative estimate of the actual trend.  New with this version we provide uncertainty statistics. More details can be found in Schweiger et al. 2011.  Model improvement is an ongoing research activity at PSC and model upgrades may occur at irregular intervals.  When model upgrades occur, the entire time series will be reprocessed and posted.

Sounds like the trend is reduced again despite last trend being conservative. If the volume keeps being adjusted upwards and the trend reduced, then it allows more time for a long tail as shown by models to make an appearance.

I would caution here... Beware the exponential function.  Higher numbers may not indicate an emerging "tail" so much as they indicate 1 or 2 two more years of grace before a thorough crash.

I would also add higher numbers now do not preclude higher numbers *earlier*; this revision suggests to me that it is possible they started higher (40 years ago) and have fallen farther.
This space for Rent.