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Glen Koehler

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Re: 2019 vs 2012
« Reply #100 on: July 28, 2019, 11:37:59 PM »
If 2019 melt season to date has been above average, then why project the 2019 end of season as being just average rather than projecting it to be equally above average? Gerontocrat's post for today identifies extent loss for 2019 as 6.9% greater than average from the 2019 maximum. Would it not be more reasonable to use that same 6.9% greater than average loss for the rest of the year.
It is all projection and as they say in investing past performance is no guarantee of future performance but it would make more sense to base the projections on the current year than on an average of past years wouldn't it? There is some validity to the current year building momentum and to the current condition of ice compared to ice from what ice was on average over the past 8 years.

I third that idea.  Would be interesting to add to the 2011-2018 avg remaining losses to minimum for parallel projections.  Gets at the issue that Arctic behavior could be in new functional state such that even recent past averages are not the best or at least not the only reasonable expectation for current situation. 

This stuff is certainly interesting, I just wish it did not bring with it such dread.  Great to have community to collectively chew on tthe details and the scary prospects for my kids and all of of us.  Would be even more disturbing to watch this train wreck unfold alone, would be maddening actually. 

mini-speech (again) - I work in the natural sciences (ag & biology), and if people think that the general scientist community is fully aware of the pace and prospects of what's happening our spaceship Earth, my observation is that they would be wrong.  Heck even some of the people I do climate adaptation work with do not fully get the urgency.  The scientists and other smart people I interact with know the basic trajectories, but like like all of us, our  rains focus on the day to day issues.  Hard to save the world between breakfast and dinner.

 The climate crisis is so big that it is hard to react to in specific ways. But we have to take any steps we can to push a survival agenda.  In case it's news, we are heading for deep doo doo friends.

 I'm off topic for this thread and becoming a pain in the butt with yet another iteration of this speech.  Sorry, I just can't help preaching to the choir.  I just hope all us who visit the ASIF will become irritants even if it makes us irritating and predictable to our family, friends and our larger social network.   If not those of us who watch the unfolding epic changes in minute detail, then who else? Thanks for considering this request.  I will try to stick to the data hereafter -- for a while at least.
« Last Edit: July 28, 2019, 11:44:50 PM by Glen Koehler »

Richard Rathbone

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Re: 2019 vs 2012
« Reply #101 on: July 29, 2019, 02:05:35 PM »
Glen, did you do any testing for negative skill on your techniques? If you use anomaly persistence from far enough out it has negative skill and these look like variants on the that sort of technique.

Using only relatively recent data for comparison may be good enough to avoid that problem, and 2011 makes sense as a starting year, but I wondered if there was any analysis behind that choice.

Glen Koehler

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Re: 2019 vs 2012
« Reply #102 on: July 29, 2019, 02:29:03 PM »
Hi Richard - I chose 2011-2018 simply because those are the most recent years with enough years in the set  - 8 - to get a reasonably well defined (low StdDev) average.  Zero testing.  I did want the epic 2012 in the set.  I now think that it would be good to include 2010 in the recent avg because it was also a big loss year -- #6.

Klondike Kat

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Re: 2019 vs 2012
« Reply #103 on: July 29, 2019, 05:03:07 PM »
I did a similar analysis, but went back to 2007, because that was the first big loss year. 

Using NSIDC extent data, the average loss over that time frame was 10.37m km2, with 2012 leading the way with 11.91m, followed by 2008 at 10.71, 2010 at 10.67, and 2007 at 10.61.  2016 was fifth with 10.39m. 

Using the same data on July 19, the average date at which 2/3 of the ice has melted, only 2012 retains its position at 7.78m km2.  2011 and 2013 were next, but both had their melt curtailed at the end of the summer.  Conversely, 2008 was at the low end, but witnessed enhanced melt through late September. 

Consequently, melt to date is a poor indicator of additional melt.  Hence, assuming a continued melt rate through minimum is no better than assuming average melt. 

By the way, using the current rate of melt, the minimum this year would be 3.77m, second lowest after 2012.  Using average melt, the minimum would be a little higher at 3.98m, still second lowest.  However, using the last two years of high early melt (2011 and 2013) as the benchmark for late season melt, then the minimum would be much higher at 4.48m km2. Therefore, my final projection is for a range between 3.77 and 4.48m km2 at minimum.

BenB

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Re: 2019 vs 2012
« Reply #104 on: July 29, 2019, 06:44:44 PM »
One of the areas where 2012 had significantly less ice extent on this date is the eastern Beaufort. However, on closer comparison the situation is more nuanced, and arguably 2019 looks more likely to melt out further north. In the event, 2012 then experienced quite strong melt, whereas the forecast is less "favourable" this year, so we'll have to wait and see what happens.

Glen Koehler

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Re: 2019 vs 2012
« Reply #105 on: July 30, 2019, 12:10:47 AM »
Consequently, melt to date is a poor indicator of additional melt.  Hence, assuming a continued melt rate through minimum is no better than assuming average melt.

Thanks Klondike.  I think I'll stick with using past average remaining losses from previous years and retract adding the complication of also showing estimates based on this year's anomaly vs. that average. 

Richard Rathbone comment about negative skill by using years from too far back in the average to estimate remaining losses from current date to minimum has me thinking why not just use most recent years as they must be the most relevant in a rapidly and monotonically evolving system.  So instead of 8 prior years, I might go down to the previous 5 years.  Should still be a large enough set to smooth out any single year outlier effect.  I don't really need a small standard deviation for the average.  I'm not doing probability distribution,  just a simple guess at final annual minimum based on average of remaining losses from current date to end of melt season in previous years.

I even thought of using just the most recent 3 years, but that would allow values from flukey conditions in a single year to have too much influence vs. having the average provide a good estimate of what is most likely to occur in the current year. 

I'm just guessing at all of this of course.  Not enough time or expertise to really suss out the best method, but open to suggestions.


petm

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Re: 2019 vs 2012
« Reply #106 on: July 30, 2019, 03:59:03 AM »
For a sense of what may be to come...

Single image of the median of 3 days ending July 28, 2019

vs.

Gif of 5 day lagging median, July 28 - Sept 14, 2012 (click to animate, large file).

jdallen

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Re: 2019 vs 2012
« Reply #107 on: July 30, 2019, 06:46:18 AM »
For a sense of what may be to come...

Single image of the median of 3 days ending July 28, 2019

vs.

Gif of 5 day lagging median, July 28 - Sept 14, 2012 (click to animate, large file).
Viewed like this, 2012 doesn't look like it's that far ahead.
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bbr2314

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Re: 2019 vs 2012
« Reply #108 on: July 30, 2019, 06:47:47 AM »
For a sense of what may be to come...

Single image of the median of 3 days ending July 28, 2019

vs.

Gif of 5 day lagging median, July 28 - Sept 14, 2012 (click to animate, large file).
Viewed like this, 2012 doesn't look like it's that far ahead.
Well, it is actually behind 2019, so that may be why...

petm

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Re: 2019 vs 2012
« Reply #109 on: July 30, 2019, 06:49:31 AM »
Viewed like this, 2012 doesn't look like it's that far ahead.

Indeed. Rather 2012 looks considerably and increasingly behind 2019. But what happens in a week when the effects of the 2012 GAC kick in?

jdallen

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Re: 2019 vs 2012
« Reply #110 on: July 30, 2019, 06:51:16 AM »
For a sense of what may be to come...

Single image of the median of 3 days ending July 28, 2019

vs.

Gif of 5 day lagging median, July 28 - Sept 14, 2012 (click to animate, large file).
Viewed like this, 2012 doesn't look like it's that far ahead.
Well, it is actually behind 2019, so that may be why...
My point, obscured by my attempt at being droll.
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petm

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Re: 2019 vs 2012
« Reply #111 on: July 30, 2019, 06:52:01 AM »
Oh for a second I read troll...  ;D

binntho

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Re: 2019 vs 2012
« Reply #112 on: July 30, 2019, 06:57:45 AM »
Was thinking about the effects of the GAC in 2012 and whether we will be able to prove or disprove that it had a large effect on the minimum that year.

My take is that if we have no GAC this year, then the GAC effect is only proved in the positive (by there not being a new record).

But there is no outcome this year that will be able to disprove the GAC effect since so many other variables are pushing for a record.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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petm

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Re: 2019 vs 2012
« Reply #113 on: July 30, 2019, 07:07:25 AM »
Was thinking about the effects of the GAC in 2012

I think so too (with the caveat that one point cannot make a trend). If no GAC and the melt slows in the next week or two, it's decent evidence the GAC was important. If no GAC and melt does not slow -- well this year already looks worse so it's hard to say.

My guess is still that the GAC was more imprtant than many people claim, and that as a result we will see a slow-down relative to 2012 starting in about a week and persisting to minimum. But every day I grow less convinced...

bbr2314

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Re: 2019 vs 2012
« Reply #114 on: July 30, 2019, 07:25:06 AM »
Was thinking about the effects of the GAC in 2012

I think so too (with the caveat that one point cannot make a trend). If no GAC and the melt slows in the next week or two, it's decent evidence the GAC was important. If no GAC and melt does not slow -- well this year already looks worse so it's hard to say.

My guess is still that the GAC was more imprtant than many people claim, and that as a result we will see a slow-down relative to 2012 starting in about a week and persisting to minimum. But every day I grow less convinced...
Both GFS and CMC show a significant low pressure event (sub-980mb) in the D7-10 range at 00z. Let's see if 00z EURO follows along.

petm

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Re: 2019 vs 2012
« Reply #115 on: July 30, 2019, 07:42:02 AM »
Both GFS and CMC show a significant low pressure event (sub-980mb) in the D7-10 range at 00z. Let's see if 00z EURO follows along.

If we did have a GAC this year (or anything close), I'd be very surprised if we didn't see new extent and area records (possibly by a wide margin).

binntho

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Re: 2019 vs 2012
« Reply #116 on: July 30, 2019, 07:58:20 AM »
Both GFS and CMC show a significant low pressure event (sub-980mb) in the D7-10 range at 00z. Let's see if 00z EURO follows along.

If we did have a GAC this year (or anything close), I'd be very surprised if we didn't see new extent and area records (possibly by a wide margin).
I agree - but that would still leave us guessing as to the effect of the GAC or whether all that melt was built in and would have happened anyway.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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El Cid

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Re: 2019 vs 2012
« Reply #117 on: July 30, 2019, 08:27:07 AM »
For a sense of what may be to come...

Single image of the median of 3 days ending July 28, 2019

vs.

Gif of 5 day lagging median, July 28 - Sept 14, 2012 (click to animate, large file).

Wow. I was saying that 2019 gets the silver but on these pictures 2019 looks to be everywhere (except for the Atlantic front) ahead of 2012. Starting to think about that gold medal...

BenB

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Re: 2019 vs 2012
« Reply #118 on: July 30, 2019, 09:50:45 AM »
There's a lot of talk about average melt between now and the rest of the season. That's useful for keeping the discussion grounded in reality, but you also have to look at the current conditions:

SSTs - very important to bottom melt in the run-in of the season
volume/thickness - important for obvious reasons
current ice surface conditions/albedo - makes a huge difference to how much insolation is absorbed into the system
dispersion
the weather forecast for the coming week

I would say all of these factors suggest above average melt between now and the minimum. Not necessarily equal to 2012, but almost certainly higher than usual.

For SSTs, last year Neven handily posted a comparison of conditions on 28 July for 4 recent years. I've added 2019. 2012 and 2016 both lost significantly more extent than normal between 28 July and minimum. 2017 and 2018 lost less. Which is 2019 most similar to?


sja45uk

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Re: 2019 vs 2012
« Reply #119 on: July 30, 2019, 12:19:48 PM »
For SSTs, last year Neven handily posted a comparison of conditions on 28 July for 4 recent years. I've added 2019. 2012 and 2016 both lost significantly more extent than normal between 28 July and minimum. 2017 and 2018 lost less. Which is 2019 most similar to?

In my biased/unbiased opinion 2019 is closest to 2012 and perhaps more extreme!

philopek

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Re: 2019 vs 2012
« Reply #120 on: July 30, 2019, 08:20:34 PM »
For a sense of what may be to come...

Single image of the median of 3 days ending July 28, 2019

vs.

Gif of 5 day lagging median, July 28 - Sept 14, 2012 (click to animate, large file).
Viewed like this, 2012 doesn't look like it's that far ahead.

It's 300k behind today, not ahead and has been a bit less but still ahead on the 28th.

Edit: I see it's a ninja post, this was said further down the quoted post, sorry.
« Last Edit: July 30, 2019, 08:30:06 PM by philopek »

philopek

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Re: 2019 vs 2012
« Reply #121 on: July 30, 2019, 08:24:50 PM »
Viewed like this, 2012 doesn't look like it's that far ahead.

Indeed. Rather 2012 looks considerably and increasingly behind 2019. But what happens in a week when the effects of the 2012 GAC kick in?

Since the current gap is around 300k in favor of 2019 and considering 1M loss in 7 days in 2012, an average loss of 100k will bring them to par.

But then the reminder in 2019 will be more fragmented and thinner than 2012. So chances are high that 2019 remains in the lead, especially when putting into account that there are still 3 days to go where 2012 was a stalling a bit and the gap could increase from 300k to 500k even, provided that 2019 won't suffer a similar slow down during the next 3 days which is the unknown today.
« Last Edit: July 30, 2019, 08:30:44 PM by philopek »

Klondike Kat

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Re: 2019 vs 2012
« Reply #122 on: July 30, 2019, 08:26:17 PM »
My eyeballing of the five graphs yielding the following ratings for each region from worst (warmest/least ice) to best (coldest/most ice):


Beaufort: 2012, 19, 17, 16, 18
Chukchi:     19, 17, 18, 16, 12
E. Siberian: 17, 16, 19, 18, 12
Laptev:       12, 19, 18, 17, 16
Kara:          16, 12, 19, 17, 18
Barents:      16, 18, 12, 19, 17
Greenland:  16, 17, 18, 12, 19
Baffin:         12, 19, 16, 17, 18

2019 appears to be faring a little better on the Atlantic side, but worse elsewhere.  Anyone else?

Sterks

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Re: 2019 vs 2012
« Reply #123 on: July 30, 2019, 08:36:50 PM »
Beaufort: 2012, 16, 19, 17, 18
That image doesn’t make justice to the level of melting going on in Beaufort in 2016.

Tor Bejnar

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Re: 2019 vs 2012
« Reply #124 on: July 30, 2019, 09:55:07 PM »
Taking KK's rankings and providing an inverse weighting (1st place gets 5 points, 2nd - 4, etc.), I get "How bad it is" weighted values:

Year   Weighted
          Value
2012     26
2016     27
2017     23
2018     18
2019     26

This makes 2019 look tied with 2012.  2016 'had the potential' but later faded.
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petm

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Re: 2019 vs 2012
« Reply #125 on: July 31, 2019, 12:37:35 AM »
Since the current gap is around 300k in favor of 2019 and considering 1M loss in 7 days in 2012, an average loss of 100k will bring them to par.

But then the reminder in 2019 will be more fragmented and thinner than 2012. So chances are high that 2019 remains in the lead

I'm not so sure. It seems likely that effects of the GAC lasted for not just a week, but right through to minimum (and beyond).

philopek

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Re: 2019 vs 2012
« Reply #126 on: July 31, 2019, 12:55:29 AM »
Since the current gap is around 300k in favor of 2019 and considering 1M loss in 7 days in 2012, an average loss of 100k will bring them to par.

But then the reminder in 2019 will be more fragmented and thinner than 2012. So chances are high that 2019 remains in the lead

I'm not so sure. It seems likely that effects of the GAC lasted for not just a week, but right through to minimum (and beyond).

Agree, I'm also not so sure. I don't dare to look out to far from now because there is so much time left for storms and other things to surprise us ;)

My outlook was meant about 20 days out, should have mentioned it, thanks for this important add-on.

BenB

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Re: 2019 vs 2012
« Reply #127 on: August 01, 2019, 10:38:13 AM »
Taking KK's rankings and providing an inverse weighting (1st place gets 5 points, 2nd - 4, etc.), I get "How bad it is" weighted values:

Year   Weighted
          Value
2012     26
2016     27
2017     23
2018     18
2019     26

This makes 2019 look tied with 2012.  2016 'had the potential' but later faded.

Accepting KK's rankings, it's interesting that those results tie in with what actually happened. Correlation, but not necessarily causation. Incidentally, I'd say that 2019 is worse than 2012 in Greenland, and only clearly behind 2016, because although the ice front is slightly further south, there's much more heat in the adjoining waters. But these things are subjective, and in general KK's rankings look about right.

Killian

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Re: 2019 vs 2012
« Reply #128 on: August 03, 2019, 11:38:49 AM »
8/01/2019 = -51k
                = 5.91M km sq., a record low for the date.

8/02/2019 = -60k, or 5.85M

Daily Change to Exceed 2012 Record Daily Lows

8/03/2012 = 6.03M km sq.
8/02/2019 = Gain of < 180k km sq. required for the record.

 Call it -65k+/-10k to 5.785 (5.79).

Analysis: I don't see anything that's going to change the daily numbers much for 8/03. We've had a 40k, 50k, and 60k day in the last three days largely because, imo, the wind direction favors expansion of the sea ice, particularly in areas where concentration is low allowing for easy wind effect. That still holds: Winds coming off of the CAA and Greenland aid compaction, but there's precious little space to move with the main ice pack sitting there; winds from Svalbard to Russia generally favor expansion, but the island chain is there and there are some crossing winds muching things up. There's a cyclone straddling the Bering Strait which currently  should be creating a net expansion of ice. Later in the day this one moves north of the CAA and another is entering the Bering Strait... cancelling each other out?

A push. Another middling day mostly because all the mush on the Pacific side and along Siberia should continue melting, plus a little help along the CAA and Greenland.

Caveat: All that mush. A bunch of it could melt away due to the cyclones.

Daily Changes Needed to Exceed 2012 low on Aug. 10. (Related to effect of GAC and it's import vs. 2019's melt cycle.)

8/10/2012 stood at 4.94M km sq.
2019 needs an average daily drop of > 113.75k km sq. for a record low on this post-GAC date. (9 days.)

I fully expect 2019 to have a higher extent than 2012 sometime between the 5th and 7th, and much more likely the 5th or 6th than the 7th except for the "caveat" above. We could see very little actual ice loss over the next 8 days and still see a huge drop in extent if that mush melts away.

Daily Changes Needed to Exceed 2012 Record Low on Sept. 15. (Related to comparison of 2012 vs 2019's melt cycle.)

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 60.68k km sq. for a record low on this date. (45 days)

This still has a fair chance of happening, but gets less likely each day these small meltouts happen. The caveat is... the above caveat. There's an awful lot of low concentration ASI right now and if that all melts out, things will be getting interesting.

Will 2019 get it's "big week in June" and/or "big week in August?"
« Last Edit: August 03, 2019, 11:54:28 AM by Killian »

Shared Humanity

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Re: 2019 vs 2012
« Reply #129 on: August 03, 2019, 02:01:01 PM »
nice analysis...

Stephan

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Re: 2019 vs 2012
« Reply #130 on: August 03, 2019, 09:18:39 PM »
Yes, I agree. Nice analysis and a 'Like' earned.
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Killian

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Re: 2019 vs 2012
« Reply #131 on: August 04, 2019, 12:58:55 PM »
8/03/2012 = 6.03M km sq.
8/02/2019 = Gain of < 180k km sq. required for the record.

 Call it -65k+/-10k to 5.785 (5.79).

Came in at... 8/03/19 > 5.785.

No. Effing. Way. And that, Dear Readers, is why we try new things. No, this doesn't mean I've become the Great ASIE Whisperer (more wrong than even within the ballpark so far, I'm pretty sure), but it does say, hey, this may be within the realm of possibility.

All that said...

-----------------------------
Daily Change to Exceed 2012 Record Daily Lows

8/04/2012 = 5.79M km sq.
8/03/2019 = Loss of > 10k km sq. required for the record. (10k is just a round number acknowledging using only two decimal poiints leaves significant daily error.)

Call it -75k +/-15k km sq.

Analysis:

What a tough day to call. We've got a big cyclone crossing from the Beaufort to north of the CAAS/Greenland over the day, thus affecting ice over a wide area and turning wind different directions during different parts of the day.

Early in the day the winds are mostly for expansion, but later in the day more for compaction. And then there's all that mush.

Quote
Caveat: All that mush. A bunch of it could melt away due to the cyclones.

I don't see much change in that mush for what is currently visible on Worldview. Weirdly, the ice in the Beaufort around the US/Can border... isn't moving, or there's an artifiact from the timing of slices of the mosaic. Elsehwhere, it's expanding, going sideways, contracting... holy hell...

What there does seem to be is a lot of heat entering still (by a lot I mean 1 - 5C, depending) according to NullSchool. I think the effects of the large cyclone will manifest more during the following days than the 4th with stirring up a little bit of heat, plus all the arm air around the edges. Honestly, I think this is much more an ASI Area killer than an ASIE killer.

I really don't know what to expect for the 4th. Going with gut as much as anything.... highly scientific... so the large error range.

Daily Changes Needed to Exceed 2012 low on Aug. 10. (Related to effect of GAC and it's import vs. 2019's melt cycle.)

8/10/2012 stood at 4.94M km sq.
2019 needs an average daily drop of > 121.43k km sq. for a record low on this post-GAC date. (9 days.)

Quote
I fully expect 2019 to have a higher extent than 2012 sometime between the 5th and 7th, and much more likely the 5th or 6th than the 7th except for the "caveat" above. We could see very little actual ice loss over the next 8 days and still see a huge drop in extent if that mush melts away.

Nothing new here to say.

Daily Changes Needed to Exceed 2012 Record Low on Sept. 15. (Related to comparison of 2012 vs 2019's melt cycle.)

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 60.70k km sq. for a record low on this date. (45 days)

Nothing new here to discuss...
« Last Edit: August 04, 2019, 03:32:57 PM by Killian »

Neven

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Re: 2019 vs 2012
« Reply #132 on: August 04, 2019, 02:48:11 PM »
2019 warmer overall than 2012 during July, much warmer on Atlantic, slightly more warming on Pacific, cooler on Siberian, much cooler on Canadian:
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Killian

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Re: 2019 vs 2012
« Reply #133 on: August 04, 2019, 03:36:57 PM »
Positive feedback appreciated. Part of the reason I do this is these are numbers that work for me, that I want to see, so I assumed at least a few others would, also.

As they say, and as a teacher, I mean it, if I help even one...

Cheers

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Re: 2019 vs 2012
« Reply #134 on: August 04, 2019, 03:52:51 PM »
Positive feedback appreciated.

The ice disagrees.  ;D

Killian

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Re: 2019 vs 2012
« Reply #135 on: August 05, 2019, 03:34:49 AM »
Positive feedback appreciated.

The ice disagrees.  ;D

No kidding. Think we're near the limit for positive feeback loops.

Killian

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Re: 2019 vs 2012
« Reply #136 on: August 05, 2019, 06:59:36 AM »
Call it -75k +/-15k km sq.

Another reasonably good call. ASIE dropped 70k (about 66k actual, I think) to 5.72, within my *generous* margin of error. Nice, though, that the rounded error is within 5k since I use the rounded numbers from the JAXA graph. Even the unrounded came in at less than a 10k deviation and I usually use a 10k +/- error . I think we get to call this a victory, eh?

Note on Method:

1. Look at wind directions and temps via Nullschool. Primary data.
2. Look at Worldview actual ice movement. Mostly the previous day's ice, but I can see a little of the day being predicted at the time I predict, which can help confirm the wind forecasts.
3. Look at info posted by others on the forums here, so whatever others happen to post.

This is enough to get reasonably accurate predictions on occasion. I've not been able to make it any more sophisticated than that, so far, but for extent, wind, currents and bottom melt will be key because we don't need any change in area or volume to get changes in extent; ice movement is enough, so ultimately I decided winds are the central data needed. Energy in the system - heat - is likely what I'd look at for area with storms next.

FYI, in case anyone is curious and it wasn't already obvious.

-----------------------------

Daily Change to Exceed 2012 Record Daily Lows

8/05/2012 = 5.65M km sq.
8/04/2019 = Loss of > 70k km sq. required for the record.

*Note the very large 140k drop for 2012.*

Call it -85k +/-10k km sq.

Analysis:
There seems to be/may be a lot of the slush ice melting because of the high temps flowing in to the Chukchi, ESS, Laptev and Beaufort Seas. And that, quite simply, tells the tale for 8/05.

Looks like 2019 has at least a 50% chance of retaining the record one more day. No more than that, I'm fairly certain. Look for '19 and '12 to be very, very close on the 5th. If my prediction is correct, '19 should be lower by a smidgen.

Daily Changes Needed to Exceed 2012 low on Aug. 10. (Related to effect of GAC and it's import vs. 2019's melt cycle.)

8/10/2012 stood at 4.94M km sq.
2019 needs an average daily drop of > 129.83k km sq. for a record low on this post-GAC date. (7 days.) (Sorry... yesterday's was 8, not 9.)

Done. This just isn't going to happen. However, with the reduction - if my prediction holds - and the fluff in the Chukchi and Beaufort starting, on the 5th, to really diminish, it's worth watching to the end. The way the extent edge is determined means there's a lot of area that can suddenly disappear still.

Daily Changes Needed to Exceed 2012 Record Low on Sept. 15. (Related to comparison of 2012 vs 2019's melt cycle.)

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 60.45k km sq. for a record low on this date. (42 days) <-- Also wrong yesterday.

Without some big days over the next week, it gets a lot less likely '19 challenges the record. that number has to be down to 20k by Sept 1.

petm

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Re: 2019 vs 2012
« Reply #137 on: August 06, 2019, 01:33:23 AM »
Looks like we'll be getting something of an answer to the controversy over how important the GAC was to the record melt in 2012. This date in 2012 was when the GAC hit and the melt rate (area/extent decline), which had been starting to shallow out like most years, picked up again.

This year, although it's difficult to directly compare years, today we have nearly equal area, extent and PIOMAS volume as 2012. And we have no major storms in the forecast. So, if area/extent begin shallowing out now (at least until a storm hits if one does), as seems very likely to me, does it provide evidence that the 2012 GAC was decisive or at least important in the 2012 records?

Aug4 2019 vs. 2012, 5-day lagging median, cross-fade gif att. (Click)
« Last Edit: August 06, 2019, 01:39:38 AM by petm »

oren

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Re: 2019 vs 2012
« Reply #138 on: August 06, 2019, 03:06:36 AM »
So, if area/extent begin shallowing out now (at least until a storm hits if one does), as seems very likely to me, does it provide evidence that the 2012 GAC was decisive or at least important in the 2012 records?
IMHO that would not be enough evidence. As Friv says, 2012 was primed to lose a lot of vulnerable ice on the ESS side. The thing is, 2019 is in the same situation, though the amount of ice on the block is somewhat lower. So should a GAC come along, all that ice is gone in a flash, but if no GAC arrives, that ice will still melt out in a couple of weeks. So immediate slowdown vs. 2012 is not proof enough - it shows the GAC brought the melt forward, not that it made a difference to the record.
The question is: does it take a GAC to sustain melt momentum into late August and Sept. in 2012 and 2016 the GACs were the immediate suspects of such late melting, what we need is 2019 to serve as the control group - lots of warmth, lots of momentum, no GAC, possibly season tapers off and dies down. Good for the ice, good for the experiment. Still not sure it will happen though - there could be a GAC, or there could be continued melt without a GAC. We'll know in a few weeks.

peterlvmeng

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Re: 2019 vs 2012
« Reply #139 on: August 06, 2019, 03:31:01 AM »
So, if area/extent begin shallowing out now (at least until a storm hits if one does), as seems very likely to me, does it provide evidence that the 2012 GAC was decisive or at least important in the 2012 records?
IMHO that would not be enough evidence. As Friv says, 2012 was primed to lose a lot of vulnerable ice on the ESS side. The thing is, 2019 is in the same situation, though the amount of ice on the block is somewhat lower. So should a GAC come along, all that ice is gone in a flash, but if no GAC arrives, that ice will still melt out in a couple of weeks. So immediate slowdown vs. 2012 is not proof enough - it shows the GAC brought the melt forward, not that it made a difference to the record.
The question is: does it take a GAC to sustain melt momentum into late August and Sept. in 2012 and 2016 the GACs were the immediate suspects of such late melting, what we need is 2019 to serve as the control group - lots of warmth, lots of momentum, no GAC, possibly season tapers off and dies down. Good for the ice, good for the experiment. Still not sure it will happen though - there could be a GAC, or there could be continued melt without a GAC. We'll know in a few weeks.

Oren, I think the storm comes from either warmer SST or cold troposphere. As you can see storm form frequently in the periphery of arctic region because of warm SST. In 2016, the troposphere in Arctic is not warm maybe even cold so we also see lots of storm. As the arctic SST is rising and troposphere is cooling. Trust me, we will see numerous strong cyclone in arctic region in the late August.
« Last Edit: August 06, 2019, 03:56:44 AM by peterlvmeng »

petm

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Re: 2019 vs 2012
« Reply #140 on: August 06, 2019, 03:50:14 AM »
As Friv says, 2012 was primed to lose a lot of vulnerable ice on the ESS side.

I'm ambivalent about this proposition. It seems to suggest that a *slower* melt on the periphery (or at least the ESS) should lead to a lower minimum. Also, this year has more vulnerable ice in the Beaufort, CAB, Atlantic, and Greenland sea. If 2012 had not had the GAC, wouldn't that ESS ice have been protective of the adjacent CAB ice. Look how long it's taking the few final wisps of the ESS to melt out this year compared to how suddenly the far more substantial ESS ice melted out in 2012.

Quote
The question is: does it take a GAC to sustain melt momentum into late August and Sept. in 2012 and 2016 the GACs were the immediate suspects of such late melting, what we need is 2019 to serve as the control group - lots of warmth, lots of momentum, no GAC, possibly season tapers off and dies down.

I'd say yes, and that it is not a separate question from the question of immediate melt. Sure, we shall see...

Alphabet Hotel

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Re: 2019 vs 2012
« Reply #141 on: August 06, 2019, 04:54:17 AM »

Oren, I think the storm comes from either warmer SST or cold troposphere. As you can see storm form frequently in the periphery of arctic region because of warm SST. In 2016, the troposphere in Arctic is not warm maybe even cold so we also see lots of storm. As the arctic SST is rising and troposphere is cooling. Trust me, we will see numerous strong cyclone in arctic region in the late August.

That's my gut feeling as well. All that heat has to go somewhere, and a storm (or storms) are the usual way to dissipate it.

Glen Koehler

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Re: 2019 vs 2012
« Reply #142 on: August 06, 2019, 09:01:21 AM »
    Arctic Sea Ice Scorecard updated for Extent and Area through August 4.
Part 1 of 3 posts. 
     Still using 2011-2018 average losses from current date to September minimum as baseline for predicting 2019 minimums. 
    Post by Klondike Kat indicated that season to date anomaly vs. average loss rate was not a good predictor for remainder of year losses.  KK data also indicated that due to variability between years, using a more recent but smaller set of years would not give a reliable average.











Glen Koehler

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Re: 2019 vs 2012
« Reply #143 on: August 06, 2019, 09:07:50 AM »
Arctic Sea Ice Scorecard --  Volume and Thickness* values updated through July 31.
Post 2 of 3.
  (* There was an error in Thickness values in the first scorecard posted on July 26.  Thickness values corrected in this edition.)





Glen Koehler

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Re: 2019 vs 2012
« Reply #144 on: August 06, 2019, 09:59:09 AM »
Arctic Sea Ice Scorecard
Post 3 of 3.



Observations/Speculation: 
-- 2012 stands alone as the lowest overall with 1st place ordinal rankings for all four measures.  (Technically, 2019 minimum thickness was lower, but only by insignificant margin.) 
The index value for each year is based on its average of ratios to the minimum value observed in 1979-2019 for each measure, not by the average ordinal ranking.

-- 2019 is second to lowest, with one 1st, and three 2nd place rankings.  The estimated 2019 minimums for Extent and Area are substantially larger than for 2012.  The 2019 and 2012 minimums for Volume and Thickness are similar. 

-- 2016 and 2011 are close to each other for 3nd lowest overall ranking, followed by 2010 and 2017 in a virtual tie for 4th place. 

-- Heading into 2012, the prior two years -- 2010 and 2011  -- were ranked #2 and #1 (now 5 and 4), which suggests that the 2012 minimum records may have been the culmination of a three year sequence of predisposing bad melt years vs. being entirely due to conditions in 2012. 
 
-- Except for 2007, there is a high degree of congruence between the 2D measures (Extent, Area) and the the 3D measures (Volume, Thickness). 

-- Nine of the 10 lowest ranking years have been in the last decade (all except 2007 at #9).



This report is not sanctioned by the National Snow and Ice Date Center, the Polar Science Center, or any other institution.  This report is a personal effort to make the situation of Arctic sea ice decline easier to understand as an indicator for the rapidly progressing and accelerating planetary climate crisis. 

Perspectives:


---------------------

The following image shows Arctic albedo loss across 7 years. 
But it is outdated now because it only includes 3 of the top ten smallest minimum Extent years.  Current albedo reductions relative to a 2000-2004 baseline must be much higher.



« Last Edit: August 06, 2019, 10:17:05 AM by Glen Koehler »

philopek

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Re: 2019 vs 2012
« Reply #145 on: August 06, 2019, 12:48:49 PM »
@glen

Absolutely top notch contribution, one of the most impressing I've seen kudos.

Perhaps a remark that doesn't mean to take anything away from the data you provided, just
slightly different angle from where i look at things:

- We shall see most certainly ABOVE average melt, not just average

To me that means that we shall see a tighter race while i currently see the final result like your
calculations do, just tighter and i could imagine that volume will be lowest this year, not only thickness.


Killian

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Re: 2019 vs 2012
« Reply #146 on: August 06, 2019, 01:01:26 PM »
8/04/2019 = Loss of > 70k km sq. required for the record.

There seems to be/may be a lot of the slush ice melting because of the high temps flowing in to the Chukchi, ESS, Laptev and Beaufort Seas. And that, quite simply, tells the tale for 8/05.

Call it -85k +/-10k km sq.

Correct analysis, wrong number. Fell 107k to 5.61M km sq., 12k more than my max. Encouraging: Got the increased melt,/lower extent right.

Daily Change to Exceed 2012 Record Daily Lows

8/06/2012 = 5.49M km sq.
8/05/2019 = Loss of > 120k km sq. required for the record.

*Note the very large 160k drop for 2012.*

Call it -75k +/-10k km sq.

And, that, Dear Readers, would be the end of 2019's record run, likely for the rest of the melt season. With the huge drops coming for 2012, there's really no chance 2019 holds the record after the 6th, but we could see that 120k given the 5ths 107k. But don't count on it.

Analysis:
Quote
There seems to be/may be a lot of the slush ice melting because of the high temps flowing in to the Chukchi, ESS, Laptev and Beaufort Seas. And that, quite simply, tells the tale
for 8/06, too. The difference is a lot less balance in wind directions supporting compaction vs expansion. Temps are pretty high in the Laptev and Chukchi, the only areas with solid chances of compaction, flowing into the ice, though, and some of the strongest winds for the day flow in those two areas.

The caveat is, as always, that wispy mush melting or not. Could have a huge drop if it goes poof. 150k? Worldview suggests it isn't going to happen on the 6th, though.

-------------------------------

Daily Changes Needed to Exceed 2012 low on Aug. 10.
(Related to effect of GAC and it's import vs. 2019's melt cycle.)

8/10/2012 stood at 4.94M km sq.
2019 needs an average daily drop of > 134k km sq. for a record low on this post-GAC date. (5 days.)

Despite the 107k loss for the day, the daily average rose bc of the large drop, and there are 5 straight 100k+ days coming with a 150k, 160k, and a 190k day all ahead.

Daily Changes Needed to Exceed 2012 Record Low on Sept. 15.
(Related to comparison of 2012 vs 2019's melt cycle.)

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 59.27k km sq. for a record Sept. low. (41 days)

After 7 days sitting at 60k, the avg finally dropped to 59k, but without some big days over the next week, it gets a lot less likely '19 challenges the record.

Klondike Kat

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Re: 2019 vs 2012
« Reply #147 on: August 06, 2019, 03:12:35 PM »
@glen

Absolutely top notch contribution, one of the most impressing I've seen kudos.

Perhaps a remark that doesn't mean to take anything away from the data you provided, just
slightly different angle from where i look at things:

- We shall see most certainly ABOVE average melt, not just average

To me that means that we shall see a tighter race while i currently see the final result like your
calculations do, just tighter and i could imagine that volume will be lowest this year, not only thickness.

Agree.  Glen did an excellent job.  I believe in his calculations that he is using above average melt, as he is assuming that the melt to date (which is above average) will constitute the same overall fraction of the total melt as previous years.  I am curious to see how his numbers match with the final tally.

binntho

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Re: 2019 vs 2012
« Reply #148 on: August 06, 2019, 03:21:57 PM »
Agree, very interesting.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

philopek

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Re: 2019 vs 2012
« Reply #149 on: August 06, 2019, 03:24:21 PM »
@glen

Absolutely top notch contribution, one of the most impressing I've seen kudos.

Perhaps a remark that doesn't mean to take anything away from the data you provided, just
slightly different angle from where i look at things:

- We shall see most certainly ABOVE average melt, not just average

To me that means that we shall see a tighter race while i currently see the final result like your
calculations do, just tighter and i could imagine that volume will be lowest this year, not only thickness.

Agree.  Glen did an excellent job.  I believe in his calculations that he is using above average melt, as he is assuming that the melt to date (which is above average) will constitute the same overall fraction of the total melt as previous years.  I am curious to see how his numbers match with the final tally.

Ok, thanks, that evaded me, perhaps the frequent occurrence of the word "average" made me partially blind for details. Your help is much appreciated.