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Author Topic: Latest PIOMAS update (November 2019)  (Read 1062416 times)

Vergent

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Re: Latest PIOMAS update (April)
« Reply #550 on: April 06, 2015, 09:54:08 AM »
jdallen,

Sorry for coming out of hibernation, but PIOMAS volume units are Km^3, and they are kilo, not mega. You are off by a factor of 1,000. This makes it difficult to take you seriously.

 Verg

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Re: Latest PIOMAS update (April)
« Reply #551 on: April 06, 2015, 11:21:57 AM »
I think jdallen was referring to Cryosphere Today sea ice area numbers, which, I admit, is a bit confusing in the PIOMAS thread.  :)
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Re: Latest PIOMAS update (April)
« Reply #552 on: April 06, 2015, 04:27:19 PM »
As I've said before, I don't think 2-dimensional measures at this time of year are remotely relevant to what ice will be there in September.
How to frame this... the state of the ice *currently* is not specifically predictive of the state it will be in in September - I generally agree.
You are contradicting yourself. Using differences between max and min to infer min IS THE SAME THING as inferring min from max!

I disagree.  I'm not using the max to infer the eventual min.  I'm using the loss of ice extent to infer a possible range of minimum values, not a specific one.

By doing that I'm looking at two very broad variables.  First is the total uptake of heat, as identifiable by changes in ice coverage and ocean temperature.  The second is weather, as expressed in the same loss of ice.

So no, I can't infer a specific minimum.  I can infer from recent behavior a predictable loss of extent.  *That* has been reasonably consistent at just under 10 million KM2. 

However, the sample is fairly small, and has some pretty serious outliers (8.5 million and 12 million), so the chance exists for minima that reflect those losses.  That said, they *are* 2 sigma results.  most actually favor my base assumption of just under 10 million KM2.

We'll see how the season plays out.

You're splitting hairs. Your technique still uses the max to infer the min, to within some range of uncertainty. Is that better?

jdallen

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Re: Latest PIOMAS update (April)
« Reply #553 on: April 06, 2015, 04:54:56 PM »
I think jdallen was referring to Cryosphere Today sea ice area numbers, which, I admit, is a bit confusing in the PIOMAS thread.  :)

Oops :)  Sorry.  I can re-work it with PIOMAS :))
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oren

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Re: Latest PIOMAS update (April)
« Reply #554 on: April 07, 2015, 02:46:37 PM »
So, from this consider the probable outcome for 2015.

If we have a sea ice loss which is "average", what would the minimum look like?

Applying the 1979-2014 average we get a max of 13.27 million KM2. (values in millions of KM2)


                      Using 1979-2014 stats      Using 2000-2014 stats
From Average   3.40                               3.06
From Median     3.45                               3.03
+2SD              2.22                                1.88
-2SD               4.58                                4.25

It's a big range, but its also pretty easy to see that given relatively normal melt, the ice coverage is quite likely to flirt with the lowest of years we've seen.

Even a "cool" melt year still keeps us generally within what we saw in 2013 and 2014.

I believe the possible problem with such a calculation is that loss might be slightly correlated to max extent, meaning that in high max years more ice is lost than low max years, which in turn causes the low correlation of the min to the max even though losses are fairly grouped together.
In the real world, if the Sea of Okhotsk is full of ice and this causes high max extent, when it melts out the loss will be high, and vice versa, buit the min extent (driven by CAB and CAA and whatever) will still be the same.
I haven't done the calculation to check this, my math skills are rusty.

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Re: Latest PIOMAS update (April)
« Reply #555 on: April 07, 2015, 03:00:07 PM »
I believe the possible problem with such a calculation is that loss might be slightly correlated to max extent, meaning that in high max years more ice is lost than low max years, which in turn causes the low correlation of the min to the max even though losses are fairly grouped together.
In the real world, if the Sea of Okhotsk is full of ice and this causes high max extent, when it melts out the loss will be high, and vice versa, buit the min extent (driven by CAB and CAA and whatever) will still be the same.
I haven't done the calculation to check this, my math skills are rusty.
Oren see the thread I  started on the Plateau  hypothesis which suggests exactly the reverse of your thoughts.
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jdallen

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Re: Latest PIOMAS update (April)
« Reply #556 on: April 07, 2015, 04:23:50 PM »
I believe the possible problem with such a calculation is that loss might be slightly correlated to max extent, meaning that in high max years more ice is lost than low max years, which in turn causes the low correlation of the min to the max even though losses are fairly grouped together.
In the real world, if the Sea of Okhotsk is full of ice and this causes high max extent, when it melts out the loss will be high, and vice versa, buit the min extent (driven by CAB and CAA and whatever) will still be the same.
I haven't done the calculation to check this, my math skills are rusty.
Oren see the thread I  started on the Plateau  hypothesis which suggests exactly the reverse of your thoughts.
Still not an unreasonable criticism.  I started tinkering with the PIOMAS volume data, and found the variability - about 1000KM3 - probably too high to be useful for prediction; not much more it seemed than saying the Arctic will melt a lot in summer, and freeze a lot in fall. I'll post what I have later. Perhaps one of you can imagine more utility than my meager skills do.
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Re: Latest PIOMAS update (April)
« Reply #557 on: May 05, 2015, 09:25:31 AM »
PIOMAS gridded data was updated (still waiting for the main daily data and graphs).

Here are the maps with monthly average thickness of April 2014, 2015 as well as the difference.

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Re: Latest PIOMAS update (April)
« Reply #558 on: May 05, 2015, 09:28:08 AM »
And difference in growth from March to April,  red means more thickening/less thinning.

seaicesailor

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Re: Latest PIOMAS update (April)
« Reply #559 on: May 05, 2015, 11:50:41 AM »
PIOMAS shows thickening north of Alaska, right where NSIDC shows substantial loss of concentration. Can this be congruent or one contradicts each other? I'd say loss of concentration must reduce average thickness (unless transport brought very thick ice up there)

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Re: Latest PIOMAS update (April)
« Reply #560 on: May 05, 2015, 12:04:24 PM »
PIOMAS shows thickening north of Alaska, right where NSIDC shows substantial loss of concentration.

If you check the Radarsat images on the 2015 melt thread you can see that older ice has indeed moved into the vicinity of Point Barrow over the last few weeks:



 
« Last Edit: May 05, 2015, 12:13:50 PM by Jim Hunt »
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jdallen

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Re: Latest PIOMAS update (April)
« Reply #561 on: May 05, 2015, 05:06:59 PM »
PIOMAS gridded data was updated (still waiting for the main daily data and graphs).

Here are the maps with monthly average thickness of April 2014, 2015 as well as the difference.

Encouraging, but perhaps that is illusory hope. 

For example at the same time as I see improved thickness in say, the CAA, I note the area where the tragic loss of two dutch explorers occurred shows a thickness of over two meters.

I suspect the conditions have become so granular, areas of thick and thin ice have become so small and intermixed, that its beyond the ability of the sensors to resolve properly. 

River ice might be a good metaphor.  During breakup, it might actually be thicker than when it was static, but it certainly isn't in better shape, nor safe to cross....
« Last Edit: May 05, 2015, 05:14:54 PM by jdallen »
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Re: Latest PIOMAS update (April)
« Reply #562 on: May 05, 2015, 05:38:31 PM »
I was wondering about ice conditions in the areas with highest reported thickness when I saw the report about the researchers who had died in that area, and the description of "open water and poor ice conditions."

http://forum.arctic-sea-ice.net/index.php/topic,1247.0.html

http://www.nunatsiaqonline.ca/stories/article/65674two_dutch_researchers_presumed_drowned_in_nunavut/

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Re: Latest PIOMAS update (April)
« Reply #563 on: May 05, 2015, 07:16:15 PM »
(still waiting for the main daily data and graphs).

Quote
2015  91  24.059
2015  92  24.084
2015  93  24.118
2015  94  24.150
2015  95  24.182
2015  96  24.201
2015  97  24.232
2015  98  24.248
2015  99  24.261
2015 100  24.275
2015 101  24.277
2015 102  24.295
2015 103  24.289
2015 104  24.277
2015 105  24.266
2015 106  24.281
2015 107  24.306
2015 108  24.332
2015 109  24.358
2015 110  24.377
2015 111  24.388
2015 112  24.354
2015 113  24.307
2015 114  24.273
2015 115  24.205
2015 116  24.168
2015 117  24.136
2015 118  24.107
2015 119  24.078
2015 120  24.066

jai mitchell

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Re: Latest PIOMAS update (April)
« Reply #564 on: May 05, 2015, 11:28:27 PM »
for an average monthly value of 24.231  Which places the April value back below the 2010 high point.   (March was slightly above the 2010 value)

It looks like the early minimum did impact the volume values somewhat.
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crandles

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Re: Latest PIOMAS update (April)
« Reply #565 on: May 05, 2015, 11:50:26 PM »
Year 2015 2010
Mar 23.236 23.121
Apr 24.232 24.103

Looks to me like 2015 had more volume than 2010 in Mar and Apr averages, but I could easily have done something stupid.

jdallen

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Re: Latest PIOMAS update (April)
« Reply #566 on: May 06, 2015, 12:53:32 AM »
Year 2015 2010
Mar 23.236 23.121
Apr 24.232 24.103

Looks to me like 2015 had more volume than 2010 in Mar and Apr averages, but I could easily have done something stupid.
Not sure.

I will say that when considered in context to the measurements confidence ranges, are statistically equivalent.  "Higher" or "lower" with such small differences are almost meaningless adjectives.
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jai mitchell

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Re: Latest PIOMAS update (April)
« Reply #567 on: May 06, 2015, 02:08:17 AM »
indeed,

according to http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/PIOMAS.2sst.monthly.Current.v2.1.txt

March 2010 = 23.082
March 2015 = 23.206
Delta = .124

April 2010 = 24.097
April 2015 = 24.222
Delta = .125



Thats what I get for eyeballing a trendline. . .  ::)
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Wipneus

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Re: Latest PIOMAS update (May)
« Reply #568 on: May 06, 2015, 08:35:22 AM »
(still waiting for the main daily data and graphs).

Quote
2015  91  24.059
...
2015 120  24.066

Indeed, everything has been updated now, including the subject line of this thread.

Wipneus

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Re: Latest PIOMAS update (June)
« Reply #569 on: June 04, 2015, 07:43:23 AM »
Updated, graphs are in the top post.

(gridded data updated also, I will post the graphs later)

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Re: Latest PIOMAS update (June)
« Reply #570 on: June 04, 2015, 07:49:27 AM »
Here are the maps with monthly average thickness of May 2014, 2015 as well as the difference.

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Re: Latest PIOMAS update (June)
« Reply #571 on: June 04, 2015, 07:51:05 AM »
And difference in growth from April to May,  red means more thickening/less thinning.


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Re: Latest PIOMAS update (June)
« Reply #572 on: June 04, 2015, 09:12:50 AM »
So ESS is thick as hell.
 

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Re: Latest PIOMAS update (June)
« Reply #573 on: June 04, 2015, 10:27:23 AM »
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Yuha

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Re: Latest PIOMAS update (June)
« Reply #574 on: June 04, 2015, 11:01:57 AM »
So ESS is thick as hell.

Except that MODIS reveal this:

Remember that it is not the end of May thickness but the average thickness for the whole of May.

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Re: Latest PIOMAS update (June)
« Reply #575 on: June 04, 2015, 11:16:16 AM »
Thanks for the graphs and maps, Wipneus. I've used a couple for the PIOMAS 2015 June update over on the ASIB.
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Re: Latest PIOMAS update (June)
« Reply #576 on: June 04, 2015, 11:22:39 AM »
So ESS is thick as hell.

Except that MODIS reveal this:

Remember that it is not the end of May thickness but the average thickness for the whole of May.


Indeed that is not fair, here is the last day available, 31th of May.

Wipneus

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Re: Latest PIOMAS update (June)
« Reply #577 on: June 04, 2015, 11:56:09 AM »
animated.

oren

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Re: Latest PIOMAS update (June)
« Reply #578 on: June 04, 2015, 12:35:00 PM »
Just as things get going nicely, it stops...
« Last Edit: June 05, 2015, 01:35:23 PM by oren »

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Re: Latest PIOMAS update (June)
« Reply #579 on: June 05, 2015, 11:36:08 AM »
Here is the last day available, 31th of May.

Can you easily do an Arctic wide version for May 31st?
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Wipneus

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Re: Latest PIOMAS update (June)
« Reply #580 on: June 05, 2015, 04:30:38 PM »
Here is the last day available, 31th of May.

Can you easily do an Arctic wide version for May 31st?

Yes.

Colored the land in "tomato3" (R speak). I hope that alerts you these are from the daily data, not the usual monthly files. Give it a click of course.

Jim Hunt

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Re: Latest PIOMAS update (June)
« Reply #581 on: June 05, 2015, 04:53:25 PM »
Yes. Colored the land in "tomato3" (R speak). I hope that alerts you these are from the daily data, not the usual monthly files.

Thanks very much Wipneus. I clicked it eventually!
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jai mitchell

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Re: Latest PIOMAS update (June)
« Reply #582 on: June 06, 2015, 12:02:47 AM »
what is the May monthly average value?
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Re: Latest PIOMAS update (June)
« Reply #583 on: June 06, 2015, 03:55:48 PM »
well, had PIOMAS not pathetically walled access to their data, one could tell instantly...

Apart from that, why should one care at that level? There is cryosat and given the divergence of last year's PIOMAS values versus cryosat volume, I would tend to stick with the latter...

OSweetMrMath

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Re: Latest PIOMAS update (June)
« Reply #584 on: June 07, 2015, 07:14:36 AM »
well, had PIOMAS not pathetically walled access to their data, one could tell instantly...

In what way has PIOMAS walled access to their data? It all appears to be downloadable from the usual location.

On the other hand, it doesn't look like the data file for the monthly average has been updated. Not the first time this has happened. I think Wipneus calculates a monthly average from the daily average for the graphs. Eyeballing puts the May average volume at about 23.0 thousand cubic km.

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Re: Latest PIOMAS update (June)
« Reply #585 on: June 07, 2015, 12:04:04 PM »
well, had PIOMAS not pathetically walled access to their data, one could tell instantly...

Let's not go there. The people from the PSC are extremely responsive and willing to share data, but they're working on other stuff too. You know, doing science etc. I don't think it's their top priority to have everything available real-time for a handful of interested amateurs. And it shouldn't be.

Ask them (or some of us here) if you need anything.
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Re: Latest PIOMAS update (June)
« Reply #586 on: June 07, 2015, 12:28:33 PM »
well, had PIOMAS not pathetically walled access to their data, one could tell instantly...

Apart from that, why should one care at that level? There is cryosat and given the divergence of last year's PIOMAS values versus cryosat volume, I would tend to stick with the latter...

Puzzled...

Cryosat makes assumption of snow depth, if that assumption is wrong then Cryosat is wrong.

jai mitchell

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Re: Latest PIOMAS update (June)
« Reply #587 on: June 07, 2015, 01:47:35 PM »
well, had PIOMAS not pathetically walled access to their data, one could tell instantly...

In what way has PIOMAS walled access to their data? It all appears to be downloadable from the usual location.

On the other hand, it doesn't look like the data file for the monthly average has been updated. Not the first time this has happened. I think Wipneus calculates a monthly average from the daily average for the graphs. Eyeballing puts the May average volume at about 23.0 thousand cubic km.

that is what I got too, but For some reason it seems high to me. . .
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Re: Latest PIOMAS update (June)
« Reply #588 on: June 07, 2015, 01:55:00 PM »
on a similar and slightly related note:

May snow cover anomalies are updated



here is the map, look at Alaska!

 :o



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http://climate.rutgers.edu/snowcover/chart_vis.php?ui_year=2015&ui_month=5&ui_set=2
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Re: Latest PIOMAS update (June)
« Reply #589 on: June 07, 2015, 09:07:30 PM »
Right, now I see what you all mean, Jinlun has forgotten to update the monthly data, as has been noted it has happened before. I will email him tomorrow.

Not a problem right now though. For 1979 to 2014 the RMS error of my volume calculations based on gridded data vs the monthly PIOMAS figures for May is 96ppm.

I calculate May average volume as 23.019k km^3, call it 23.02k km^3 (+/- 1 digit). OSMM is correct in his guesstimate.

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Re: Latest PIOMAS update (June)
« Reply #590 on: June 07, 2015, 09:14:09 PM »
on a similar and slightly related note:

May snow cover anomalies are updated



here is the map, look at Alaska!

 :o



Rutgers Snow lab
http://climate.rutgers.edu/snowcover/chart_vis.php?ui_year=2015&ui_month=5&ui_set=2

This suggests huge region-wide drops in Albedo well before we enter the teeth of the melt season.  It suggests the streaming of heat and moisture into the arctic basin proper will not be letting up.
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Re: Latest PIOMAS update (June)
« Reply #591 on: June 07, 2015, 11:55:51 PM »
@OSweet: Mea culpa. I had the habit of using the parent directory:
http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/

To get to the data, which is walled now. Number two is the introduction of the email query, which actually makes a link pop up, but I needed your unhappy response to actually find it, as it is tiny and nearly invisible in my browsers. Must say, I looked a long time for the data and then (mistakenly) gave up.

@ChrisReynolds: You should be careful about snow cover and cryosat, taking all blame on the data. As snow cover affects PIOMAS in a similar direction (insulating the ice from heat losses), an underestimate of snow cover will lead to overestimated ice volumes in PIOMAS, or am I mistaken?

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Re: Latest PIOMAS update (June)
« Reply #592 on: June 08, 2015, 09:47:40 AM »
on a similar and slightly related note:

May snow cover anomalies are updated



here is the map, look at Alaska!

 :o



Rutgers Snow lab
http://climate.rutgers.edu/snowcover/chart_vis.php?ui_year=2015&ui_month=5&ui_set=2

stupid question:
is the snow anomaly in alaska lack of precipitation, possibly related to that california drought?  or did it melt early?  (or some combination of the 2...)

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Re: Latest PIOMAS update (June)
« Reply #593 on: June 08, 2015, 11:32:32 AM »
on a similar and slightly related note:

May snow cover anomalies are updated



here is the map, look at Alaska!

 :o



Rutgers Snow lab
http://climate.rutgers.edu/snowcover/chart_vis.php?ui_year=2015&ui_month=5&ui_set=2

stupid question:
is the snow anomaly in alaska lack of precipitation, possibly related to that california drought?  or did it melt early?  (or some combination of the 2...)

Early melt, for a large part of May abnormally hot weather kept the place anywhere from 10-20C above base line average as per GFS. This torched much of the snow cover.

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Re: Latest PIOMAS update (June)
« Reply #594 on: June 08, 2015, 12:43:20 PM »
You should be careful about snow cover and cryosat, taking all blame on the data.

The latest NASA IceBridge/CryoSat results for March have been published. More background at:

http://forum.arctic-sea-ice.net/index.php/topic,1149.msg53595.html#msg53595

but here's the maps again:



Reality is merely an illusion, albeit a very persistent one - Albert Einstein

ChrisReynolds

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Re: Latest PIOMAS update (June)
« Reply #595 on: June 08, 2015, 06:48:07 PM »
@ChrisReynolds: You should be careful about snow cover and cryosat, taking all blame on the data. As snow cover affects PIOMAS in a similar direction (insulating the ice from heat losses), an underestimate of snow cover will lead to overestimated ice volumes in PIOMAS, or am I mistaken?

What I am saying is that many people make the mistake of seeing Cryosat as inherently superior to a reanalysis like PIOMAS or NAME. Cryosat is not inherently superior because it suffers from the same issue of uncertainty over snow depth and distribution.

quanitlaq

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Re: Latest PIOMAS update (June)
« Reply #596 on: June 08, 2015, 07:04:34 PM »

stupid question:
is the snow anomaly in alaska lack of precipitation, possibly related to that california drought?  or did it melt early?  (or some combination of the 2...)
[/quote]

Early melt, for a large part of May abnormally hot weather kept the place anywhere from 10-20C above base line average as per GFS. This torched much of the snow cover.
[/quote]

Alaska had a warm winter and low snow year plus a warm May - so likely a combination of the 2. Many of us in Alaska that like snow blamed Boston for stealing it, but scientists are pointing to the warm "blob" in the eastern North Pacific, which has also been implicated for the California drought to some degree.

Vergent

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Re: Latest PIOMAS update (June)
« Reply #597 on: June 08, 2015, 09:43:01 PM »
Wipneus or Chris,

Could you do May 2015 - 2012 ice thickness and snow thickness? ("-" = minus)

Thanks

Verg

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Re: Latest PIOMAS update (June)
« Reply #598 on: June 08, 2015, 11:31:54 PM »
Vergent,

Map or regional volume?

Wipneus may be the best bet for a map, since I re-wrote my code to tidy up, difference maps would need a total rewrite to get them running (it's complicated..). But regional figures I can do.

Volume and thickness, for May average, difference between 2012 and 2015 = 2015 - 2012.
Also for context 2012 volume for May and the percent change.

Volume in km^3.
   Difference / 2012 Vol / %  Change
Other   0.0   0.0   0.00%
Okhotsk   -42.2   108.2   -39.03%
Bering   -221.7   261.3   -84.84%
Beaufort   -257.9   1098.1   -23.49%
Chukchi   -238.0   1394.9   -17.06%
ESS   -149.2   2032.3   -7.34%
Laptev   -0.6   1049.1   -0.06%
Kara   242.4   624.5   38.82%
Barents   176.0   193.2   91.13%
Greenland   -62.0   650.4   -9.53%
Central   1535.1   10557.6   14.54%
CAA   54.0   1473.8   3.67%
Baffin   184.3   962.3   19.15%
Hudson   83.6   1309.0   6.39%
All   1303.9   21714.7   6.00%
Arctic Ocean   1299.9   19073.9   6.81%


Thickness in metres.         
   Difference / 2012 Vol / %  Change
Other   0.00   0   0.00%
Okhotsk   -0.16   0.63   -25.25%
Bering   -0.28   0.49   -56.85%
Beaufort   -0.48   2.11   -22.50%
Chukchi   -0.40   2.39   -16.77%
ESS   -0.17   2.28   -7.34%
Laptev   0.00   1.64   -0.06%
Kara   0.28   0.83   34.33%
Barents   0.31   0.63   49.90%
Greenland   0.04   0.82   4.52%
Central   0.35   2.38   14.54%
CAA   0.07   1.95   3.67%
Baffin   0.17   0.92   18.38%
Hudson   0.08   1.14   6.90%
All   0.17   1.74   9.63%
Arctic Ocean   0.13   1.98   6.79%

Hope that's of use.

PS Beaufort is the thinnest and lowest volume on record!

Neven

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Re: Latest PIOMAS update (June)
« Reply #599 on: June 08, 2015, 11:54:20 PM »
Quote
PS Beaufort is the thinnest and lowest volume on record!

But that's where a lot of the MYI is...  ??? :-\
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