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What will the CT 2013 Arctic SIA daily minimum be?

More than 3.5 million km2
4 (7.4%)
Between 3.25 and 3.5 million km2
7 (13%)
Between 3.0 and 3.25 million km2
10 (18.5%)
Between 2.75 and 3.0 million km2
14 (25.9%)
Between 2.5 and 2.75 million km2
5 (9.3%)
Between 2.25 and 2.5 million km2
6 (11.1%)
Between 2.0 and 2.25 million km2
5 (9.3%)
Between 1.75 and 2.0 million km2
1 (1.9%)
Between 1.5 and 1.75 million km2
0 (0%)
Between 1.25 and 1.5 million km2
0 (0%)
Between 1.0 and 1.25 million km2
0 (0%)
Between 0.75 and 1.0 million km2
1 (1.9%)
Between 0.5 and 0.75 million km2
0 (0%)
Between 0.25 and 0.5 million km2
0 (0%)
Between 0 and 0.25 million km2
1 (1.9%)

Total Members Voted: 52

Voting closed: August 11, 2013, 06:01:45 PM

Author Topic: Cryosphere Today 2013 Arctic SIA daily minimum: August poll  (Read 81059 times)

Neven

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Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« on: August 04, 2013, 06:01:45 PM »
THIS POLL WILL RUN FOR ONE WEEK (until August 11th). YOU CAN CHANGE YOUR VOTE. MIND THE DIFFERENCES WITH THE NSIDC SEA ICE EXTENT MONTHLY/SEPTEMBER MINIMUM. THIS IS CT SEA ICE AREA DAILY MINIMUM.

Attention: Because it's this year's last poll, you have only one week to vote!


Same text as last month's poll:

It should be 'fun' and interesting to hold a poll each month, to see how opinions change according to sea ice rhythm and pace. These monthly polls can then also function as a dedicated thread for everything concerning Cryosphere Today sea ice area. Daily updated data can be found here.

Again, this poll is for Cryosphere Today sea ice area daily minimum (unlike the other popular measure: NSIDC sea ice extent monthly minimum), so we're looking for the lowest total Arctic sea ice area number on any given day at the end of the 2013 melting season.

Here's how things are currently looking based on data up to August 2nd:



These are the daily minimums for the last 7 years (in millions km2):

    2005: 4.092
    2006: 4.030
    2007: 2.919
    2008: 3.004
    2009: 3.425
    2010: 3.072
    2011: 2.905
    2012: 2.234

Again, try to use this thread to discuss CT SIA mainly. There are other threads for the other topics, and if there isn't, feel free to open one.
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Neven

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #1 on: August 04, 2013, 06:12:40 PM »
Went up another bin to 2.75-3.0, with CT acting so crazy lately.
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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #2 on: August 04, 2013, 07:54:58 PM »
I'm sticking with 3.22 to 4.15M km^2, as voted in last months poll.

I've voted for the top category - over 3.5M, but retain an option for the category below as it's in the range of my prediction. My probability density function would peak around 3.7M km^2. Having just checked I did actually vote for the category below in July's vote.



The bounds of my mathematical prediction are indicated as +/-SD and Central, I have previously narrowed this to within Central and -SD in the June poll.

Having seen:

1) PIOMAS data - the recent levelling in CT Area has been a real arrest of melt. I had thought it was mainly due to dispersion, which held open the possibility of a rapid drop afterwards.
2) GFS and ECWMF predict more serious low pressure, which implies the same conditions that caused CT Area to level after 25 July. That takes us to almost 1/3 of August with little prospect of a 1.8M loss, which would be needed to get to 3M km^2 by minimum.

3) NCEP/NCAR for July showing how weird the weather is in the context of other 2007 to 2012 years. Thus indicating we're not about to see an assertion of the summer pattern in August.

I am willing to make a further prediction - nobody else will vote in the same bucket.  ;D

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #3 on: August 04, 2013, 11:00:57 PM »
I went with 2.5-2.75. I think this year ain't finished with the surprises quite yet!
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Richard Rathbone

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #4 on: August 05, 2013, 12:28:20 AM »
I'm still working from the baseline of PIOMAS volume anomaly at minimum being about the same as at May 31, and the PIOMAS/CT thickness staying the same and adjusting if PIOMAS behaves diverges from the track I'd expect it to follow to get there.

 PIOMAS slipped a little from my forecast track and it looks like the May-Min melt will be in the lower end of the range. Last time I was around 2.75 but in the 2.5-2.75 bin, and that slow down at the end of July is more than enough to push me above 2.75.

Its close enough to the end of the year to take a look at the graphs and see where they look like they are trending.
Looking at the regional records my ranges for the ones I think might have ice are:
CAB 2.5-3.0
CAA 0.15-0.25
Beaufort 0-0.1
ESS 0-0.05
Laptev 0-0.05
Total 2.65-3.45

I think it would take something pretty unusual during the rest of the year to end up outside 2.5-3.5, and I'm actually going with 2.75-3.0 due to innate scientific conservatism and not wanting to move any further from my previous guess than I have to.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #5 on: August 05, 2013, 04:20:16 AM »
This lull in ice loss is very puzzling.  Has all the bottom melt stopped?  I understand that the weather is making it difficult for melting but these continued upward adjustments make it seem like refreezing has already begun.  The big ice grinder is not yet on the horizon and may not materialize.  I went up 1 bucket to 3.25-3.5 while I wait for more information to confirm what exactly is happening.  I may go up to the last bucket just to be on the safe side.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #6 on: August 05, 2013, 06:21:30 AM »
Using 5-day smooth CT SIA. The graph ends on Aug 31st. Though it's probably obvious the starting date is cherry-picked to be the first day of the standstill showing on this dataset. _______________________________________________________________________________
« Last Edit: August 05, 2013, 11:54:36 AM by Pmt111500 »

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #7 on: August 05, 2013, 09:07:51 AM »
I voted more than 3.5Mkm2.

We have had months of predictions that the broken-up ice pack is about to 'melt out any day now'. This has just not happened, as the Arctic has remained stubbornly cold throughout.

Observing the images from the two buoys (O-Buoys 7 and 8 ), I've noticed regular surface freeze-thaw cycles indicating that, even at 74.5o, the temperature is hovering around 0C.

I think the arctic is not going to get much warmer, and indeed could start cooling down, by the middle of the month.
I will go out on a limb, and predict an ice area minimum before the beginning of September  ;D.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #8 on: August 05, 2013, 09:38:16 AM »
EDIT on 11 August 2013...

Have bumped my prediction up by one sigma. Now:

2.75-3.00 bin.
Prediction is 2.9 +/- 0.7 million km^2


The reason is that the storm didn't do enough. I still expect losses this August to beat 2012's record for August, with lots of ice on the Eastern side that is even more vulnerable after the storm. However, the vulnerable ice is mostly where the ice had already largely disappeared by this time last year, while the ice off Alaska is a long way behind...

10 August 2013:


10 August 2012:




Original post (now revised)...
2.00-2.25 bin.
Prediction is 2.2 +/- 0.7 million km^2

I bumped up 0.2 million km^2 from last month after another poor month for melting. The central value of 2.2 million km^2 is the same as last year's value - so I'm saying it is about 50-50 that we will beat last year's record.

The uncertainty value is unchanged at 0.7 million km^2 as I still don't have a good idea of which way the melt is going to go.
This is a 1-sigma uncertainty - so about a 2/3 chance of between 1.5-2.9 million km^2.

Am I correct in saying that this year has had a lot more area with concentration well below 100% than any previous year with data? I still think that is going to take its toll over the coming month. By how much is the big question.

  If the predicted cyclone comes off in the next week then that might potentially break up the ice still further as well as stir up some warmer, saltier water into contact with it. That, as well as further weather favourable for melt, might push us below 2012. On the other hand, another month unfavourable to melting could leave us well above 2012.
« Last Edit: August 11, 2013, 04:24:42 AM by slow wing »

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #9 on: August 05, 2013, 09:46:32 AM »
Am I correct in saying that this year has had a lot more area with concentration well below 100% than any previous year with data?
No. Area has plateaued even more than extent, meaning that the average concentration is sharply up relative to previous years. Overall compactness (area/extent) is towards the upper end of the recent historical record.

Neven

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #10 on: August 05, 2013, 11:41:26 AM »
Am I correct in saying that this year has had a lot more area with concentration well below 100% than any previous year with data?
No. Area has plateaued even more than extent, meaning that the average concentration is sharply up relative to previous years. Overall compactness (area/extent) is towards the upper end of the recent historical record.

But that doesn't make sense, right? Not after the PAC a couple of weeks ago, last week's big cyclone, and cyclonic activity overall, not to mention all the holes that can be seen on LANCE-MODIS and Wipneus/Uni Hamburg SIC maps.

Here's the latest CAPIE plot I used for ASI 2013 Update 6:



And the text:

Quote
This year is almost 14% more compact than 2012! This can't be due to convergence of the ice pack because of the cyclones we have had so far, which caused a lot of divergence, pushed the ice floes away from each other, creating holes within the ice pack. So again, the only possible reason I can come up with is freezing melt ponds, perhaps combined with ice floes falling apart in small pieces that spread apart, but don't melt out just yet. But even if that were the case, that still would't explain it.

This is crazy. :-)
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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #11 on: August 05, 2013, 11:55:35 AM »
I expect major drops with this huge Dipole/Cyclone.

I went with 3.0 to 3.25km2.

Up one tier from last month.  Only to be a bit safe.  But I won't be surprised if it goes below 3.0 mil.

The forecast is insane.
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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #12 on: August 05, 2013, 12:21:03 PM »
Look at that.  That will be free-falling back down shortly.  Wait until our long fetch of warm 25-35KT winds sets up.



« Last Edit: August 05, 2013, 12:50:28 PM by frivolousz21 »
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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #13 on: August 05, 2013, 12:43:30 PM »
Update: -87k9  At 4.7897081 lowest value, beating July 25 by a meager 6k.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #14 on: August 05, 2013, 01:00:21 PM »
So again, the only possible reason I can come up with is freezing melt ponds, perhaps combined with ice floes falling apart in small pieces that spread apart, but don't melt out just yet. But even if that were the case, that still would't explain it.
Hi Neven,

  I like your explanation. It makes sense to me. But why do you say it wouldn't explain it?

  Isn't it true that the area algorithms have trouble with melt ponds? Indeed, isn't that the reason, or at least a reason, why extent has become established as an alternative measure, because it suffers less from this defect?

  With this year a bit colder than in recent years, it is possible that the melt ponds may have all frozen over earlier in the season than in previous years. (And why is this year a bit colder? Speculatively, could it be that all the cracks and openings in the ice are keeping the air temperature in closer equilibrium with the sea water temperature - at about -2 degrees C, or whatever it is?)

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #15 on: August 05, 2013, 02:04:26 PM »
If you compare the CAB area from CT with the CAB area from Wipneus, you'll see that when its warm and melt starts CT drops earlier than Wipneus. Its the same in the other areas, but most obvious in the CAB because its big. As an area melts out, or it cools towards the end of the season they come back together again. The difference is mostly melt ponds. The cameras show melt ponds forming as CT area drops faster than Wipneus and freezing/draining as the CT area comes back up to Wipneus.

If you just look at CT area over a period when there are changes in melt ponding, and don't allow for the melt ponding, you'll get your expectations whipsawed as the surface melts and freezes.

That's what has happened recently. There's been a melt pond cycle. The CT graph for the CAB shows a notch as the surface melts and drains/refreezes, but Wipneus's  graph is fairly smooth.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #16 on: August 05, 2013, 04:42:18 PM »
Getting now quite the hang of calculating extent and area from concentration maps, here are the first results of the NSIDC files. I mean the files used for the NSIDC sea ice index.
The ice concentrations are calculated using the NASA Team algorithm, same as Cryosphere Today.

The attached image more or less confirms this, there is a slight bias but that is almost totally explained by the "near real time" file version, the "final" version (available to 2012) does have a much smaller difference.

It confirms also that CT lags other real time data by two days. From todays data I predict CT declines in the next two days:
Aug 6: -103k
Aug 7: -80k

« Last Edit: August 05, 2013, 04:47:51 PM by Wipneus »

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #17 on: August 05, 2013, 05:06:01 PM »
Quote
It confirms also that CT lags other real time data by two days. From todays data I predict CT declines in the next two days:
Aug 6: -103k
Aug 7: -80k

Exciting, Wippert!  :D
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Pmt111500

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #18 on: August 05, 2013, 05:21:39 PM »
Oh,
Quote
It confirms also that CT lags other real time data by two days. From todays data I predict CT declines in the next two days:
Aug 6: -103k
Aug 7: -80k

Thanks again, but this means I'll have very little to do and contribute as soon as someone figures out how to intergrate CT SIA to AMSR2! Well it's progress, and maybe I should move to using AMSR2 numbers too.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #19 on: August 05, 2013, 05:29:18 PM »
Oh,
Quote
It confirms also that CT lags other real time data by two days. From todays data I predict CT declines in the next two days:
Aug 6: -103k
Aug 7: -80k

Thanks again, but this means I'll have very little to do and contribute as soon as someone figures out how to intergrate CT SIA to AMSR2! Well it's progress, and maybe I should move to using AMSR2 numbers too.

My original intention was and still is with others, to calculate the true "CAPIE"-like ice compactness.

Side benefit is that, by this reverse engineering,  it is getting more and more clearer to me how the CT numbers are produced.


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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #20 on: August 06, 2013, 02:24:35 PM »
From todays data I predict CT declines in the next two days:
Aug 6: -103k
Aug 7: -80k

Actual decline reported on Aug 6 : -92k4

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #21 on: August 06, 2013, 02:41:40 PM »
For the next 10 days, average reductions for the last 5 years are about 46k/day, so even maintaining a loss of close to 90k/day would have catch up quite quickly.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #22 on: August 06, 2013, 02:53:03 PM »
After watching a slushy looking Arctic from very early onthat I thought was going to hit a new record I now believe that 2013 is not going to be a record year.  After watching the "DMI Daily Arctic mean temperatures north of 80N" all season and expecting it to break out above average at some point it has stayed below average all summer which has matched the limited extent and area so I am going with a 3.25-3.5 minimum. Even though things seem to be starting to happen it is all too late.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #23 on: August 06, 2013, 04:10:53 PM »
Let me see how this goes.

Day that CT reportsPredictionActual
20130806-103-92k4
20130807-80?
20130808-57?

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #24 on: August 06, 2013, 04:21:08 PM »
Let me see how this goes.

Day that CT reportsPredictionActual
20130806-103-92k4
20130807-80?
20130808-57?

So is it by the 8th on that table, it will be showing the reduction for the 5th?
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #25 on: August 06, 2013, 04:33:55 PM »

So is it by the 8th on that table, it will be showing the reduction for the 5th?

Yup, NSIDC and Jaxa report the daily values of the 7th but CT is 2 day behind.

See the graph that I attached yesterday where I shifted CT data according to that.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #26 on: August 07, 2013, 01:07:42 PM »
New CT value is in :

Day that CT reportsPredictionActual
20130806-103-92k4
20130807-80-72k2
20130808-57?

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #27 on: August 07, 2013, 02:18:11 PM »
CT Area like Extent is effected by Atmosphere, surface conditions(melting, melt ponds, fresh snow, melting snow, melting ice, diurnal swings, ice thickness, clouds, clouds, clouds, clouds. :)

Anyways.  Many of the recent years didn't experience a cold mid level blanket of air like this circle the arctic.  They also didn't have June's so cold, cloudy, with later snow melt starts.  In fact quite a bit of the ice sheet never had it's snow melt off.  Or melt much at all. 

Well not quite a bit.  But areas that would normally show up as some phantom area drops didn't materialize.

 However as the incoming just started bad weather pattern warms things up and reduces the ice coverage it will fall.  Especially after the warm air arrives.


For instance.  The Beaufort area is now down to about 110-115K.

Really?  based on CTs map.  The black line is the Beaufort/CAB border.  How can the Beaufort really be down to 110K?  What am I missing here?

Does CT use a higher res than they show in their charts?  Isn't area only grid  squares with ZERO ice?








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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #28 on: August 07, 2013, 02:34:44 PM »
Area is the sum of concentration in each cell, not cells with ice in them. Extent is cells with ice in them (defined as 15% concentration). The concentration average in there is pretty low so the area is too.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #29 on: August 07, 2013, 02:40:30 PM »
For instance.  The Beaufort area is now down to about 110-115K.

Really?  based on CTs map.  The black line is the Beaufort/CAB border.  How can the Beaufort really be down to 110K?  What am I missing here?


I calculate Beaufort as 118k7 Area and 259k4 extent.

Believe it or not.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #30 on: August 07, 2013, 02:52:39 PM »
Voted for 2,0...2,25, but i consider 2,25...2,50 nearly equally possible.

... expecting it to break out above average at some point it has stayed below average all summer which has matched the limited extent and area ...
Which, in some sense, could make us to expect something rather ugly and very melting to happen before the end of the melt season. Quite unusual for the _whole_ melt season to be cooler than was expected, is it?

Plus, i believe that relatively low temperatures this year (so far) are in fact very needed to simply stay near/at 2012 extent, because of increasing positive feedbacks. Arctic is connected with sub-polar and even mid-latitudes quite well, and last i heard, northern hemisphere as a whole keeps going south recently, with less and less ice remaining (dropping albedo), more and more ocean heat content, more greenhouse gases, more land melt water (glaciers and whatnot) ending up flowing into Arctic and so on.

The recent "halt" in the melt may perhaps be, if not entirely, then at least in significant part, an artefact of ice area measuring system - a "quirk", so to say. Showing us numbers wich are seriously higher than what there is in reality. I wrote about that in nearby poll about min september extent today in some detail, if you're interested. One additionalpossible hint to this is that different systems of measuring ice area/extent show seriously different dynamic last 2-3 weeks. This one shows big halt, some others only significant slowing, only. Perhaps the truth is further south?

I hope, though, that i am wrong and that you are right, and that this year won't see lower Arctic sea ice extent than there was in 2012. The slower Arctic goes away, the more time we humans have. Granted, most of us don't use time any well - but perhaps some few folks will use any additional time well, and perhaps in the end it'll make a big difference. Who knows.
« Last Edit: August 07, 2013, 03:00:01 PM by F.Tnioli »
To everyone: before posting in a melting season topic, please be sure to know contents of this moderator's post: https://forum.arctic-sea-ice.net/index.php/topic,3017.msg261893.html#msg261893 . Thanks!

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #31 on: August 07, 2013, 03:12:13 PM »
Area is the sum of concentration in each cell, not cells with ice in them. Extent is cells with ice in them (defined as 15% concentration). The concentration average in there is pretty low so the area is too.

Ah.  That makes sense. 



Quote
The area of sea-ice cover is often defined in two ways, i.e., sea-ice "extent" and sea-ice "area." These multiple definitions of sea-ice cover may sometimes confuse data users. The former is defined as the areal sum of sea ice covering the ocean (sea ice + open ocean), whereas the latter "area" definition counts only sea ice covering a fraction of the ocean (sea ice only). Thus, the sea-ice extent is always larger than the sea-ice area. Because of the possible errors in SIC mentioned above, satellite-derived sea-ice concentration can be underestimated, particularly in summer. In such a case, the sea-ice area is more susceptible to errors than the sea-ice extent. Thus, we adopt the definition of sea-ice extent to monitor the variation of the Arctic sea ice on this site.

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Wipneus

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #32 on: August 07, 2013, 04:02:13 PM »
Found and fixed the fault causing discontinuity between the "final", pre 2013, files and the 2013 "near real time" files. The predicted values have changed somewhat.

Day that CT reports   PredictionActual
20130806-99-92k4
20130807-83-72k2
20130808-77?
20130809-53?

F.Tnioli

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #33 on: August 07, 2013, 04:17:12 PM »
Indeed, it's sometimes impossible to know if the area is indeed what is reported, or even a less figure - and if less than reported, then for how much. Reason for this is simple: if sea ice has "holes", "srtipes" etc of open water in it which are significantly less (in size) than maximum-possible resolution of the recording apparatus (say, a satellite), - then there are simply no direct means to detect it. With much of sea ice slushed, churned, mixed etc (say, by a huge cyclone or two) - this becomes especially significant issue.

There are probably some indirect methods to detect that the ice is in fact seriously less than 100% concentration even if "holes" are too small to be directly detected and measured, - i don't know, i am no specialist, - but i bet such indirect methods wouldn't always work.

So yep, extent is much easier, can be calculated rather precisely directly from observations. However, many critically important physical processes are in fact dependant on ice area (and might i say, not on reported/calculated by modern means ice area - but on real one, which accounts even for holes/breaks of extremely small size, say, millimeter-wide). Among such processes, i guess, are evaporation, local albedo change, patterns of methane emissions (even small cracks/holes let lots of methane go out stright up - otherwise methane piles up under the "impenetrable" ice, which has its own effects, sometimes large-scale), mechanics of ice packs/fields movement - and most likely some other important processes. That's why, i guess, sea ice area, even while it can't be measured exactly precisely, is still very important to science.

Please correct me if i was wrong somewhere. Thanks!
To everyone: before posting in a melting season topic, please be sure to know contents of this moderator's post: https://forum.arctic-sea-ice.net/index.php/topic,3017.msg261893.html#msg261893 . Thanks!

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #34 on: August 07, 2013, 04:25:09 PM »
Wipneus,

CT area is filtered as a centered mean, an average of both previous and following data. The actual Julian day that data is assigned to can be gotten from the interactive graph. the most recent is JD 217, Aug 5.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #35 on: August 07, 2013, 05:00:11 PM »
Wipneus,

CT area is filtered as a centered mean, an average of both previous and following data. The actual Julian day that data is assigned to can be gotten from the interactive graph. the most recent is JD 217, Aug 5.

Vergent

See attached graph, CT is 2 days behind NSIDC. I have reported this fact before after calculating the cross correlation between CT and NSIDC ( and IJIS and my AMSR2 calc), but here it is not necessary.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #36 on: August 07, 2013, 09:43:01 PM »
For losses from 6/8/XX to min, 1979 to 2012, the best fit linear regression has a slope of -0.0005, i.e. virtually zero. Or in plain English, there is no trend to CT Area losses from 6 Aug to minimum.

The average loss is 1.020M km^2, with a standard deviation of 0.210M km^2.

CT Area as at 6 Aug 2013 (latest) is 4.625M km^2. If I apply the average loss to that I get a central estimate of the minimum, by applying the standard deviation as a +/-SD I get simple bounds of the estimate.

+SD 3.814M km^2
Cen  3.605M km^2
-SD 3.395M km^2

I'd still prefer the Central to -SD range due to thinner ice than in most of the series. However it is worth noting that some years do deviate from the average by 0.4M km^2 (twice SD) however all these years are early in the series, in the last ten years deviations have been around 1SD at maximum.

This is not a change to my prediction. Just recreational musing in a break from atmosphere oriented work.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #37 on: August 07, 2013, 10:08:46 PM »
I think Stats are great.  But unfortunately there is so many factors that are not apart of what they tell us when it comes to extent and area that can cause massive deviations.

Everything has changed so much we just don't know how things will roll with such thin ice because if we hit a stretch of bad to terrible weather for the ice from now until mid September.  Like a true blue dipole.  I guarantee area and extent would be 2nd place behind 2012 easy. 

But that would also be a huge statistical aberration.

But area and extent do not consider the two most vital factors ice thickness and weather.  With ice thickness so craptacular now.

The weather can cause radical deviations quickly.


If we had even a reliable weekly sea ice thickness update.  I mean one that is reliable not just decent at nailing volume.  But if say a bunch of up-welling just took place in the ESS region from the storm and knocked out 20-30CM off the bottom and say it bring a large area of ice to .4 to .8 meters instead of say .7 to 1.0 meters.  That could easily be the difference in 500,000km2 down the toilet or not.

Our single dimensional analysis doesn't tell us that.

Look at 2009.  It was heralded the step to recovery.  I remember quite a few 5.5 to 6.0 mil predictions all over for 2010 min go bust. 

What was ignored was that even though 2009 had much higher area and extent than the two previous years volume slightly dropped from the 2008 min.

Then in 2010 the SIE and SIA was lower than 2009 but higher than 2008 and 2007, another success.  But no, volume plummeted from 2009.  So we got 2011 and 2012. 


Do we have the July piomas ice thickness chart out yet?

I bet it didn't pick up the Eastern CAB thinning.
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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #38 on: August 08, 2013, 04:04:56 AM »


The whole Asian side of the ice cap is subject to in situ melting. The thickness is the key element to if it will do so.



TOPAZ thinks it is quite thin.



TOPAZ is predicting big losses where some of us have been expecting them.

Vergent

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #39 on: August 08, 2013, 05:36:39 AM »

Vergent,

The ice is wrecked all over the Russian side.  It is all FYI after all.






Modis looks terrible.


http://lance-modis.eosdis.nasa.gov/imagery/subsets/?mosaic=Arctic.2013219.aqua.1km
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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #40 on: August 08, 2013, 05:50:21 AM »
I'm going for 3 to 3.25 M Km2.  I'm going up maybe 2 or 3 slots.  I can't remember. 

If I were to go purely from average reduction from beginning August to end of melt I would be guessing one or two slots higher, but I'm still thinking that the state of the ice is going to have some affect on the melt.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #41 on: August 08, 2013, 06:51:36 AM »

Vergent,

The ice is wrecked all over the Russian side.  It is all FYI after all.Modis looks terrible.

Friv,

Is this a test? That is not MODIS. From the blind spot, I am quite sure it is amsr2. But, yes it looks terrible.

Vergent

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #42 on: August 08, 2013, 07:41:42 AM »

Vergent,

The ice is wrecked all over the Russian side.  It is all FYI after all.Modis looks terrible.

Friv,

Is this a test? That is not MODIS. From the blind spot, I am quite sure it is amsr2. But, yes it looks terrible.

Vergent

No Man.

I the MODIS link was at the bottom of the post.

I forgot that I cropped the AMSR2 channel 89 image, my bad.  So it left the name off.
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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #43 on: August 08, 2013, 07:57:41 AM »
The enviro Canada animations are near real time. The 3um & 11um give an indication of temps.
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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #44 on: August 08, 2013, 11:37:55 AM »
Arctis ROOS, "Norsex" area has reached now the end of the plateau.

(image attached: log in to view)

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #45 on: August 08, 2013, 02:41:14 PM »
For months, I've bet on the 1.25-1.5 bin, with the idea that the young ice on the Eastern side would melt out by late July/early August, helped by warm winds from the continent, and much more melt in the Beaufort Sea than actually happened so far, also as a result of weather.
Then a regular storm would be enough to destroy the layering in the then-open ocean (no longer relatively fresh water above more salt water), making refreezing at high latitudes more difficult and thus an extension of the melt season possible.

With the present conditions, I think a value in the 3.0-3.25 bin is more realistic.

A recovery? Only of some numbers, not of the overall quality of the Arctic ice.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #46 on: August 08, 2013, 02:51:17 PM »
Updated -66k6, in my prediction table:


Day that CT reports   PredictionActual
20130806-99-92k4
20130807-83-72k2
20130808-77-66k6
20130809-53?
20130810-34?

Update: added the Aug 10 prediction from today's NSIDC update.
« Last Edit: August 08, 2013, 03:58:04 PM by Wipneus »

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #47 on: August 08, 2013, 06:18:23 PM »
Frivolousz,

I bet that PIOMAS does pick up on the eastern thinning.

The issue with regards using past behaviour to predict is whether current behaviour gives such a deviation that it presents useful information. Nonetheless, having previously thought we'd see a new record I don't think so now, and haven't thought so since I've had June data. Now I seriously doubt that my early July prediction will be so wrong that it demonstrates new behaviour on the part of the pack, the same goes for the numbers I showed above.

This year however is exciting because the failed melt of 2013 is due to the lack of the summer pattern. This shows that while ice dynamics are a factor, without assistance from the atmosphere you don't get the losses of recent years. Why didn't the pattern develop this year? I suspect an interfering factor that makes its appearance in 50mb (stratosphere) geopotential heights.

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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #48 on: August 08, 2013, 07:21:35 PM »
Call me crazy, but I'm still holding out for a major, late season flash melt--down to under 1 m k^2. Look at those TOPAZ thickness maps Vergent posted above. If everything thinner than about a meter melts in the next two weeks, what's left will mostly be a swiss cheese pattern of by-then less than meter thick remaining ice that will be assaulted from all sides for the following weeks.

Meanwhile, our recent storm is drawing in warm air and pushing ice into southern waters where it will melt, compacting the rest into the CAB.

The rate of melt would have to be beyond unprecedented, but I have come to expect the unexpected from the new Arctic. (Of course, that could cut either way.)

In any case, someone has to hold down the low side of the curve  ::)
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Re: Cryosphere Today 2013 Arctic SIA daily minimum: August poll
« Reply #49 on: August 08, 2013, 07:44:21 PM »
What if the polar cell is globaly going up because of the extra heating, bringing some cold temps from the upper layers ?