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Sterks

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Re: 2019 sea ice area and extent data
« Reply #1850 on: July 27, 2019, 05:18:27 PM »
Area losses also have accelerated in the last day, I bet. But the 5-day average doesn't reflect it much.
Anyway 1 day drop acceleration doesn't mean much, but it should be followed by a few more days.

At any rate, compaction spike up makes sense given how loose the pack is and the nature of the current winds.

bbr2314

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Re: 2019 sea ice area and extent data
« Reply #1851 on: July 27, 2019, 06:53:08 PM »
Area losses also have accelerated in the last day, I bet. But the 5-day average doesn't reflect it much.
Anyway 1 day drop acceleration doesn't mean much, but it should be followed by a few more days.

At any rate, compaction spike up makes sense given how loose the pack is and the nature of the current winds.

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Neven

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Re: 2019 sea ice area and extent data
« Reply #1852 on: July 27, 2019, 08:44:15 PM »
Here's how NSIDC compactness looks in my updated spreadsheet:
Il faut comparer, comparer, comparer, et cultiver notre jardin

Shared Humanity

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Re: 2019 sea ice area and extent data
« Reply #1853 on: July 27, 2019, 08:57:30 PM »
It stalls and then starts moving up. Does this trend suggest the ice pack may be better protected in the latter stages of the melt season as more compact ice is less vulnerable?

oren

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Re: 2019 sea ice area and extent data
« Reply #1854 on: July 27, 2019, 09:34:50 PM »
For now it seems so. If area losses continue to be slow, extent will have to slow down later in the season after the rubble ice is gone. But area losses have time to pick up again.

passenger66

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Re: 2019 sea ice area and extent data
« Reply #1855 on: July 27, 2019, 10:11:40 PM »
For now it seems so. If area losses continue to be slow, extent will have to slow down later in the season after the rubble ice is gone. But area losses have time to pick up again.
This reflects my guess about the area/extent thing - low concentration extent going away means relatively low area going away (compared to extent).

Killian

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Re: 2019 sea ice area and extent data
« Reply #1856 on: July 28, 2019, 04:47:17 AM »
Interesting to see, that the lowest 15 years are the 15 last years - a big gap between 2004 and 2005 divides the data pack. No year before 2005 made it into the top fifteen.

Tiny correction: 2002 (5.51M km sq) was lower than both 2004 (5.69M km sq) and 2006 (5.63) putting it in the top 15, not 2006.

Juan C. García

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Re: 2019 sea ice area and extent data
« Reply #1857 on: July 28, 2019, 05:42:33 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

July 27th, 2019:
     6,288,296 km2, an almost century drop of -96,984 km2.
     2019 is the lowest on record.
     (2012 highlighted).
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

gerontocrat

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Re: 2019 sea ice area and extent data
« Reply #1858 on: July 28, 2019, 08:04:44 AM »
JAXA ARCTIC EXTENT :- 6,288,296 km2(July 27, 2019)

On average, 3/4 of extent loss completed.

- Extent is lowest in the satellite record (40th day this year), extent is 78 k below 2012, 465 k below 2016.
- Extent loss on this day 97 k, 8 k more than the average loss on this day of 89 k.
- Extent loss from maximum 7983 k, 518 k (6.9%) greater than the average of 7,465 k loss from maximum by this day,
- On average 75.5% of the melting season done, with 48 days to average date of minimum (13 September).

The Perils of Projections.
Average remaining melt would give a minimum of 3.87 million km2, 2nd lowest in the satellite record, 0.69 million km2 above the 2012 low of 3.18 million km2 and 0.15 million below the 2nd lowest  in 2016, 4.02 million km2.

Ice Melt Outlook The peak days of daily melt are  past. From now to minimum, on average daily extent loss will initially slowly reduce, this reduction in daily loss gradually accelerating on the approach to minimum. 

A weather remark: Over the next 5 days Greenland, Baffin Bay and the CAA will be warm, and at times hot.

The June volume data persuaded me to drop my guesstimate for the minimum  to below 4 million km2 from exactly 4 million km2. So far this seems to have been a sensible decision.
______________________________________________________________
The contrast between extent losses well above average and area losses well below average is becoming significant. Shades of the 2012 end of season melt?
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Killian

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Re: 2019 sea ice area and extent data
« Reply #1859 on: July 28, 2019, 09:45:24 AM »
7/26/2012 stood at 6.51M km sq. on this date.
7/25/2019 stands at 6.51M km sq. 2019 needs a drop > 0k km sq. for a record low on this date.

Previous day:
7/26/2019 stood at 6.39M km sq. on this date, a record low his date.

7/27/2012 stood at 6.37M km sq. on this date, a drop of 140.
7/26/2019 stood at 6.39M km sq. on this date. 2019 needed a drop > 20k km sq. for a record low on this date.

7/27/2019 stands at 6.29M km sq. on this date after a drop of @ 100k km sq., a record low for this date.

Current:
7/28/2019 stood at 6.29M km sq. on this date after a drop of 80k km sq.
7/27/2019 stands at 6.29M km sq. on this date. 2019 needs a drop > 0k km for a record low.

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

I may have my spreadsheet correct now, but...

8/10/2012 stood at 4.94M km sq.
2019 needs an average daily drop of > 89.87k km sq. for a record low on this post-GAC date. (15 days)

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 62.16k km sq. for a record low on this date. (50 days)

gerontocrat

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Re: 2019 sea ice area and extent data
« Reply #1860 on: July 28, 2019, 04:41:46 PM »
NSIDC Total Area as at 27 July 2019 (5 day trailing average)  4,451,602  km2

Whoops #6
Area loss staying at very much below average. 6 days really does mean reaching the place called significant.
                        
Total Area         
 4,451,602    km2      
-355,440    km2   <   2010's average.
-397,126    km2   <   2018
-1,136,979    km2   <   2000's average.
         
Total Area Change   -51    k   loss
Peripheral Seas   -5    k   loss
Central Seas__   -40    k   loss
Other Seas___   -6    k   loss
         
Peripheral Seas         
Bering _______   -0    k   loss
Baffin  Bay____   -1    k   loss
Greenland____   -3    k   loss
Barents ______   -1    k   loss
         
CAB Seas         
Beaufort_____   -5    k   loss
CAA_________   -1    k   loss
East Siberian__   -26    k   loss
Central Arctic_    11    k   gain
         
Kara_________    1    k   gain
Laptev_______   -7    k   loss
Chukchi______   -13    k   loss
         
Other Seas         
Okhotsk______   -2    k   loss
St Lawrence___   -0    k   loss
Hudson Bay___   -3    k   loss
- Area loss 51 k, 3 k LESS than the 2010's average loss of 54 k on this day.
- Total area 2nd Lowest, 197 k LESS than 2016, and 54 k MORE than 2012.

Area loss remains below average.

Outlook
We are in the period of maximum daily area loss that is already gently sliding down. Overall, Area losses in July to date above average, but currently trending very much downwards.

It definitely was a steep downward slope that has now greatly eased to well below average losses.

But note the exceptions - the Chukchi, the ESS and perhaps the Laptev.
The CAA should be really warm next week - and some rain.
________________________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: 2019 sea ice area and extent data
« Reply #1861 on: July 28, 2019, 04:49:57 PM »
Everything else may be in a sort of hiatus as far as area is concerned, but the Chukchi, ESS and Laptev look in a right old mess.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Steven

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Re: 2019 sea ice area and extent data
« Reply #1862 on: July 28, 2019, 05:10:47 PM »
NSIDC daily area is currently second lowest for the date, slightly behind 2012.  Losses have been sluggish in the past 10 days.  It seems likely that the difference with 2012 will grow substantially in the next several days, as 2012 nosedived in late July and early August.




(Note: data from Wipneus.  He uses leap year corrections for the anomaly data.)
« Last Edit: July 28, 2019, 05:30:38 PM by Steven »

Rich

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Re: 2019 sea ice area and extent data
« Reply #1863 on: July 28, 2019, 05:23:02 PM »
Everything else may be in a sort of hiatus as far as area is concerned, but the Chukchi, ESS and Laptev look in a right old mess.

The outcome of those battles have long been in the cards. Send the troops to the CAB, CAA and eastern Beaufort for the end of season siege.

Gondor won't surrender easily.  CAB area increased.

Alphabet Hotel

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Re: 2019 sea ice area and extent data
« Reply #1864 on: July 28, 2019, 05:51:20 PM »
NSIDC daily extent

Csnavywx

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Re: 2019 sea ice area and extent data
« Reply #1865 on: July 28, 2019, 06:40:33 PM »
Given the clear skies and very warm low-level temps, melt pond drain is a likely culprit at this point, especially around the periphery of the CAB. Some of the fast ice in the northern CAA over the last few days gives a clue.

Temperatures at Eureka have barely dropped below 10C the last 4 days and looking at BUFKIT/Skew-T profiles for both Alert and Eureka show a very warm airmass advecting poleward for the next few days (freezing levels 6-10kft, plenty of warm air advection in the column), as well as mostly clear skies or cloud limited to high altocumulus and cirrus.

Stephan

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Re: 2019 sea ice area and extent data
« Reply #1866 on: July 28, 2019, 06:54:37 PM »
Chukchi and Hudson still losing ± 10% of ice area every day, whereas Baffin and Barents slowed down significantly (OK, Baffin is almost free of sea ice).
It is too late just to be concerned about Climate Change

stjuuv

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Re: 2019 sea ice area and extent data
« Reply #1867 on: July 28, 2019, 09:41:49 PM »
Previous day:
7/26/2019 stood at 6.39M km sq. on this date, a record low his date.

7/27/2012 stood at 6.37M km sq. on this date, a drop of 140.
7/26/2019 stood at 6.39M km sq. on this date. 2019 needed a drop > 20k km sq. for a record low on this date.

7/27/2019 stands at 6.29M km sq. on this date after a drop of @ 100k km sq., a record low for this date.

Current:
7/28/2019 stood at 6.29M km sq. on this date after a drop of 80k km sq.
7/27/2019 stands at 6.29M km sq. on this date. 2019 needs a drop > 0k km for a record low.

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

I may have my spreadsheet correct now, but...

8/10/2012 stood at 4.94M km sq.
2019 needs an average daily drop of > 89.87k km sq. for a record low on this post-GAC date. (15 days)

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 62.16k km sq. for a record low on this date. (50 days)
I'm sorry, but what is the point of these posts?

Killian

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Re: 2019 sea ice area and extent data
« Reply #1868 on: July 29, 2019, 04:11:06 AM »
I'm sorry, but what is the point of these posts?

Fair question. Gerontocrat's posts, e.g., are filled with comments stating various averages, but he doesn't give what those averages are. Rather, not the numbers I do here: The average losses required to hit a given future point. (I've suggested he pop the numbers in there and then I wouldn't have any need or interest to do so. His posts are excellent, but I just want to see the actual numbers!) Also, a lot of sea ice talk is about anomalies and anomalies are sometimes too ambiguous to get my head around. I assume the same for others. I'm a pretty literal fellow; I want to see the numbers. That's what makes the most sense to me.

I also think in terms of patterns, and the ASI has them. There are very clear trends at various times of the year. It is interesting to me to look at certain key milestones in the year and the likelihood, or not, of hitting them.

The point is to illustrate the meaning of redundancy and the most probable motive is very telling.

Rather than be needlessly rude, maybe just scroll past. Or, say something useful: I also find these posts redundant and think of them as clutter. <-- No rudeness, less words, thus effort, clearly communicated. Why, then, engage in immature behavior, instead?

Juan C. García

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Re: 2019 sea ice area and extent data
« Reply #1869 on: July 29, 2019, 05:43:32 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

July 28th, 2019:
     6,190,083 km2, an almost century drop of -98,213 km2.
     2019 is the lowest on record.
     (2012 highlighted).
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

DavidR

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Re: 2019 sea ice area and extent data
« Reply #1870 on: July 29, 2019, 06:04:38 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

July 28th, 2019:
     6,190,083 km2, an almost century drop of -98,213 km2.
     2019 is the lowest on record.
     (2012 highlighted).
As can be seen from the graph, over the next  5 days 2012 had a relatively slow decline, about 150K below average. It  would not be surprising to see 2019 around 300K below 2012 by Aug 2nd when the GAC started to have an effect. The GAC period involved a loss of around 1 M Km^2 in 7 days.  I suspect 2019 can lose 700K in the same period to keep it in touch with 2012.
Toto, I've a feeling we're not in Kansas anymore

oren

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Re: 2019 sea ice area and extent data
« Reply #1871 on: July 29, 2019, 06:14:16 AM »
The red 2019 line indeed appears to be headed towards the green 2012 line on Aug 9th. However, the extent chart hides trends in area, which could suddenly slow down extent losses. Of course, area losses could accelerate as well, so stay tuned.

Edit: looking at this wonderful chart by Wipneus, I take back my comment above. It seems the NSIDC area data hides trends in UH area data which do support further extent losses with ease.
« Last Edit: July 29, 2019, 06:19:56 AM by oren »

UCMiami

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Re: 2019 sea ice area and extent data
« Reply #1872 on: July 29, 2019, 06:40:23 AM »
Oren - thanks for posting. Interesting that JAXA and UH area have such different area results over the last week compared to the NSIDC numbers

Something doesn't add up. I don't expect exact match, but generally all three have trended the same way and I can't think of a particular change in structure of the ice or a signifcant change in melt ponds or ... that would lead to this divergence.

Killian

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Re: 2019 sea ice area and extent data
« Reply #1873 on: July 29, 2019, 06:42:25 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

July 28th, 2019:
     6,190,083 km2, an almost century drop of -98,213 km2.
     2019 is the lowest on record.
     (2012 highlighted).
As can be seen from the graph, over the next  5 days 2012 had a relatively slow decline, about 150K below average. It  would not be surprising to see 2019 around 300K below 2012 by Aug 2nd when the GAC started to have an effect. The GAC period involved a loss of around 1 M Km^2 in 7 days.  I suspect 2019 can lose 700K in the same period to keep it in touch with 2012.

This is exactly what I track in my posts. If you scroll down a little later, you can see how many km sq/day is required to hit that mark. Or, scroll up and look at yesterday's number.

I post analysis of this stuff over on the 2019 melt season thread, if you'd like to discuss it. BTW, the last large drop from the GAC was on the 10th, 100k. It looks small because the preceding 138k/day average was so big; I missed it at first.

I have a spreadsheet, if you're interested, that is already set up to update the daily required losses to match/exceed the lows on Aug. 10th and Sept. 15th.

Killian

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Re: 2019 sea ice area and extent data
« Reply #1874 on: July 29, 2019, 07:11:24 AM »
Oren - thanks for posting. Interesting that JAXA and UH area have such different area results over the last week compared to the NSIDC numbers

Something doesn't add up. I don't expect exact match

The NSIDC/JAXA extents differentials are even weirder. I assume it's at least partly due to the 5-day vs. 2-day averaging. I have developed a mathematical conversion of JAXA <-> NSIDC because of the recent Day Without Data from JAXA that about broke my poor little spirit. It's got a mean and median error of 40k. Given the differentials between the two can be hundreds of km's, I guess that's not too bad.

44 days in the database.

Daily Conversion Accuracy, JAXA from NSIDC:

0km: 11% (aka correct)
0 ~ 20k: 27%
0 ~ 30k: 34%
0 ~ 50k: 59%
0 ~ 100k: 98%

Is this useful? Not really. How often are either JAXA or NSIDC down for an extended period? But maybe one of the math geniuses around here will find some use for the calculations. If someone asks, I'll post it. My maths are tortured being limited to very basic math. Others could problably get better results, or at least more efficient formulas and much better spreadsheet function.

Killian

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Re: 2019 sea ice area and extent data
« Reply #1875 on: July 29, 2019, 07:26:40 AM »
8/10/2012 stood at 4.94M km sq.
2019 needs an average daily drop of > 96.29k km sq. for a record low on this post-GAC date. (14 days)
***Edited for spreadsheet errors.***

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 62.16k km sq. for a record low on this date. (50 days)

8/10/2012 stood at 4.94M km sq.
2019 needs an average daily drop of > 96.15k km sq. for a record low on this post-GAC date. (13 days)
***Edited for spreadsheet errors.***

9/15/2012 stood at 3.18M km sq. on this date.
2019 needs an average daily drop of > 61.43k km sq. for a record low on this date. (49 days)

NOTE: Thanks to feedback, I've decided the daily change data are repetitive of efforts by Garcia and Gerontocrat and will not include them here in the future.
« Last Edit: July 29, 2019, 12:13:51 PM by Killian »

Matt

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Re: 2019 sea ice area and extent data
« Reply #1876 on: July 29, 2019, 08:04:16 AM »
Killian,

For people like myself who just don't have the time to do these numbers, i thank you very much for your efforts, it puts the data provided by Garcia and Gerontocrat into extra perspective. After all, is this not the thread where we are supposed to be analysing the "area and extent data"??? :P ;D

Killian

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Re: 2019 sea ice area and extent data
« Reply #1877 on: July 29, 2019, 09:01:02 AM »
Killian,

For people like myself who just don't have the time to do these numbers, i thank you very much for your efforts, it puts the data provided by Garcia and Gerontocrat into extra perspective.

Are you referring to the daily data, too, or just the milestone data above? And, yeah, I think it does, too.

Thanks for the feedback.

Quote
After all, is this not the thread where we are supposed to be analysing the "area and extent data"??? :P ;D

Yeah... weird, eh? When people complained of my editorializing about/doing analysis of the data, I cut that and started doing that elsewhere. Now, just posting data is a problem... on a data thread... on which pretty much everyone else editorializes/analyzes?

Can't please all the people all the time. There's only one voice here that really matters and I've never heard a peep from that one, so... Still, I'm not here to antagonize, so if all the feedback were negative, I'd stop. But you're the second person to mention my posts positively, so...

binntho

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Re: 2019 sea ice area and extent data
« Reply #1878 on: July 29, 2019, 09:14:04 AM »
Yeah... weird, eh? When people complained of my editorializing about/doing analysis of the data, I cut that and started doing that elsewhere. Now, just posting data is a problem... on a data thread... on which pretty much everyone else editorializes/analyzes?
Well it sort of grows on you, I retract any and all complaints I might have made previously!
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

Matt

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Re: 2019 sea ice area and extent data
« Reply #1879 on: July 29, 2019, 09:19:32 AM »
@Killian

Both really, i like to see what is required to reach certain milestones compared to what is currently unfolding on a daily basis with the extent numbers. Then cross reference that requirement with the average melt curve that genocrat provides. It allows for a very easy analysis of the current melting situation (on a purely numerical perspective -of course because that is what this thread is about).

 
« Last Edit: July 29, 2019, 09:25:01 AM by Matt »

DavidR

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Re: 2019 sea ice area and extent data
« Reply #1880 on: July 29, 2019, 09:35:55 AM »
Attached is a graph showing cumulative losses from August 1st to the minimum.

Despite starting with a lower extent each decade, the area lost is increasing each decade.  2012 shows up as a real outlier with the difference between 2nd placed 2016 (2.30M) and 2012 (2.90M) almost  matching the difference between 2016  and the 1980's average (1.58 M).

Note that  2008 lost 2.46M so 2016 is actually third, but I'd left  the noughties out  of the graph.
« Last Edit: July 29, 2019, 10:07:44 AM by DavidR »
Toto, I've a feeling we're not in Kansas anymore

Killian

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Re: 2019 sea ice area and extent data
« Reply #1881 on: July 29, 2019, 10:15:10 AM »
@Killian

Both really, i like to see what is required to reach certain milestones compared to what is currently unfolding on a daily basis with the extent numbers. Then cross reference that requirement with the average melt curve that genocrat provides. It allows for a very easy analysis of the current melting situation (on a purely numerical perspective -of course because that is what this thread is about).

Will put the dailies back tomorrow.

Thanks, Matt & binntho.

iceman

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Re: 2019 sea ice area and extent data
« Reply #1882 on: July 29, 2019, 11:23:39 AM »
Attached is a graph showing cumulative losses from August 1st to the minimum.

Despite starting with a lower extent each decade, the area lost is increasing each decade. 
    ....

This is quite significant. For volume, anomaly charts suggest the trend leans opposite. (I haven't scrutinized the data, which appear highly variable by year.) If so, the combination implies a shrinking but resistant end-of-season blob over time.

gerontocrat

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Re: 2019 sea ice area and extent data
« Reply #1883 on: July 29, 2019, 11:33:46 AM »
JAXA ARCTIC EXTENT :- 6,190,083 km2(July 28, 2019)

On average, just over 3/4 of extent loss completed.

- Extent is lowest in the satellite record (41st day this year), extent is 103 k below 2012, 495 k below 2016.
- Extent loss on this day 98 k, 17 k more than the average loss on this day of 81 k.
- Extent loss from maximum 8,081 k, 536 k (7.1%) greater than the average of 7,546 k loss from maximum by this day,
- On average 76.4% of the melting season done, with 47 days to average date of minimum (13 September).

The Perils of Projections.
Average remaining melt would give a minimum of 3.86 million km2, 2nd lowest in the satellite record, 0.68 million km2 above the 2012 low of 3.18 million km2 and 0.16 million below the 2nd lowest  in 2016, 4.02 million km2.

Ice Melt Outlook The peak days of daily melt are past. From now to minimum, on average daily extent loss will initially slowly reduce, this reduction in daily loss gradually accelerating on the approach to minimum. 

A weather remark: Over the next 5 days Greenland, Baffin Bay and the CAA will be warm, and at times hot. The CAA may well get some rain.

The June volume data persuaded me to drop my guesstimate for the minimum  to below 4 million km2 from exactly 4 million km2. So far this seems to have been a sensible decision. Indeed, my June guess of 3.75 to 4.25 million km2 may be at risk.
______________________________________________________________
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

be cause

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Re: 2019 sea ice area and extent data
« Reply #1884 on: July 29, 2019, 11:59:53 AM »
Indeed Gerontocrat .. you may still be overly optomistic .. but it looks like more wind is needed in the forecast to break records . b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 =  ' if only we could have seen it coming ' ...

Alphabet Hotel

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Re: 2019 sea ice area and extent data
« Reply #1885 on: July 29, 2019, 02:48:39 PM »
NSIDC daily extent

Juan C. García

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Re: 2019 sea ice area and extent data
« Reply #1886 on: July 29, 2019, 03:19:29 PM »
Killian: In this Forum every member is able to write a post, but it is a good practice to be concise and don't post too much. 7 post in less than 5 hours is a bad practice.

Let's all stay on-topic, keep it as short as possible, only quote the bits we want to reply to, not engage in meta-discussions, and take off-topic discussions elsewhere asap.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Tom_Mazanec

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Re: 2019 sea ice area and extent data
« Reply #1887 on: July 29, 2019, 03:23:38 PM »
In this Forum every member is able to write a post, but it is a good practice to be concise and don't post too much. 7 post in less than 5 hours is a bad practice.

Let's all stay on-topic, keep it as short as possible, only quote the bits we want to reply to, not engage in meta-discussions, and take off-topic discussions elsewhere asap.
Well, I post links to AGW articles, and those are coming more than 7 posts a day. Does that count?
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oren

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Re: 2019 sea ice area and extent data
« Reply #1888 on: July 29, 2019, 03:33:14 PM »
Tom, Juan means in this specific thread.
I'm okay with multiple posts, as long as they are short and/or full of relevant data.

gerontocrat

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Re: 2019 sea ice area and extent data
« Reply #1889 on: July 29, 2019, 03:36:05 PM »
NSIDC Total Area as at 28 July 2019 (5 day trailing average)  4,404,895 km2

Whoops #7
Area loss staying at very much below average. 7 days really does mean reaching the place called significant.
                        
Total Area         
 4,404,895    km2      
-349,108    km2   <   2010's average.
-406,104    km2   <   2018
-1,130,903    km2   <   2000's average.
         
Total Area Change   -47    k   loss
Peripheral Seas   -8    k   loss
Central Seas__   -33    k   loss
Other Seas___   -5    k   loss
         
Peripheral Seas         
Bering _______    0    k   gain
Baffin  Bay____   -1    k   loss
Greenland____   -7    k   loss
Barents ______   -0    k   loss
         
CAB Seas         
Beaufort_____   -8    k   loss
CAA_________   -5    k   loss
East Siberian__   -27    k   loss
Central Arctic_    22    k   gain
         
Kara_________   -2    k   loss
Laptev_______   -4    k   loss
Chukchi______   -10    k   loss
         
Other Seas         
Okhotsk______   -1    k   loss
St Lawrence___   -0    k   loss
Hudson Bay___   -4    k   loss
- Area loss 47 k, 6 k LESS than the 2010's average loss of 53 k on this day.
- Total area 2nd Lowest, 157 k LESS than 2016, and 61 k MORE than 2012.

Area loss remains below average.

Outlook
We are in the period of maximum daily area loss that is already sliding down a bit faster. Area losses in the last week currently trending very much downwards. It definitely was a steep downward slope that has now greatly eased to well below average losses.

But note the exceptions - the Chukchi & the ESS and perhaps the Laptev.
The CAA should be really warm this week - and some rain.
No Fram export - Greenland area loss accelerating.
________________________________________________________________________
Ice drift maps really interesting. I might venture to post something on the Melting thread about that.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Juan C. García

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Re: 2019 sea ice area and extent data
« Reply #1890 on: July 29, 2019, 03:38:03 PM »
In this Forum every member is able to write a post, but it is a good practice to be concise and don't post too much. 7 post in less than 5 hours is a bad practice.
Let's all stay on-topic, keep it as short as possible, only quote the bits we want to reply to, not engage in meta-discussions, and take off-topic discussions elsewhere asap.
Well, I post links to AGW articles, and those are coming more than 7 posts a day. Does that count?
There are members that make several posts in one day on the Forum, like Gerontocrat and Oren. But they are concise and/or a good analysis. So they are great. I also like new posts like the one that is making Alphabet Hotel on this thread.

But I agree with Neven, we should not engage in meta-discussions in threads like this one, or the Forum lose its value. Killian can make an analysis in this thread too, and I invite him to do it. But he has to make an effort to have a clear point and do not make 5 messages in less than 5 hours.

And of course that you (Tom) and anyone can make several posts, as long as you are contributing to a good discussion on this Forum.
« Last Edit: July 29, 2019, 04:25:14 PM by Juan C. García »
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Killian

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Re: 2019 sea ice area and extent data
« Reply #1891 on: July 29, 2019, 04:54:09 PM »
Juan C. García , Tom_Mazanec

This is all rather pedantic. WHY was there a string of posts? Discussing whether/what to post. Because someone complained. And someone else's disagreed with the complain. Or are we not to discuss when someone objects to, but others enjoy, given posts and sort out whether to post or not?

To complain about that is absurd: It's solving a problem.

Further, complaining about a highly specific sub-thread that is almost certainly not going to repeat is poor etiquette: It's dousing an ember with gasoline.

Most days there will be one post. This was a specific, anomalous case. AKA an anomaly. I think  you all understand how to handle them, yes?

C'mon, people... Context. It's a bit grating to be repeatedly called out for what so many others do, change your posting habits, but then get hit for... sorting out a disagreement.

NOTE: On any forum, raising a complaint about an event that is already settled... always invites chaos. This was already settled.

Object lesson. I hope.

LDorey

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Re: 2019 sea ice area and extent data
« Reply #1892 on: July 29, 2019, 05:39:51 PM »

NOTE: Thanks to feedback, I've decided the daily change data are repetitive of efforts by Garcia and Gerontocrat and will not include them here in the future.

Hey Killian,

I'll admit I often scroll by your posts when I don't have time, but even presenting duplicate data in a slightly different format can be good, post away, since you keep the same format day to day it's very easy to identify and skip if someone wants, and it (imo) fits the requirements of this thread... okay so that's enough discussion about the thread it's been a bin intense this year but I did have a thought that tickled my funny bone a little - we could could all form a committee with it's own thread to discuss the proper inclusion of posts on this thread and maybe other committee's for other threads...... then we'd need a thread to nominate committee members, and a seperate one to post the meeting minutes... it got funny in my head fast so I thought I'd share, cheers!

Liam

gerontocrat

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Re: 2019 sea ice area and extent data
« Reply #1893 on: July 29, 2019, 05:47:46 PM »
It has taken a lot of time and energy, successes and failures to build a library of spreadsheets and data sources. So it is a bit annoying to think people have to wade through a load of clutter to reach the data.

This is a data thread. So, please please please bring data or a new way of looking at the data (when discussion is great).
If not, bugger off.
____________________________________-
Meanwhile,

The Chukchi and the ESS continue to astonish. Observe how the graphs do not just deepen, they widen, with the profile switching from a V to a U shape. Big effect on AWP.

and even the Greenland Sea is instantly responding to no drift down the Fram.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

jdallen

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Re: 2019 sea ice area and extent data
« Reply #1894 on: July 29, 2019, 07:12:40 PM »
Attached is a graph showing cumulative losses from August 1st to the minimum.

Despite starting with a lower extent each decade, the area lost is increasing each decade. 
    ....

This is quite significant. For volume, anomaly charts suggest the trend leans opposite. (I haven't scrutinized the data, which appear highly variable by year.) If so, the combination implies a shrinking but resistant end-of-season blob over time.
I think latitude counts for a lot as the pack has shrunk.  It is also pulled North which means that the angle of incidence changes more rapidly and dramatically during the melt.  In short, while peak insulation is high, the timeframe is short, and what can practically be captured is less.

Lower latitude ice has longer timeframes to capture heat, and that capture over time will be more consistent.

At high latitude my hunch is increases in loss will be driven more by net increases in system heat over time, primarily imported from elsewhere.
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stjuuv

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Re: 2019 sea ice area and extent data
« Reply #1895 on: July 29, 2019, 09:08:25 PM »
I'm sorry, but what is the point of these posts?
Fair question. Gerontocrat's posts, e.g., are filled with comments stating various averages, but he doesn't give what those averages are. Rather, not the numbers I do here: The average losses required to hit a given future point. (I've suggested he pop the numbers in there and then I wouldn't have any need or interest to do so. His posts are excellent, but I just want to see the actual numbers!) Also, a lot of sea ice talk is about anomalies and anomalies are sometimes too ambiguous to get my head around. I assume the same for others. I'm a pretty literal fellow; I want to see the numbers. That's what makes the most sense to me.

I also think in terms of patterns, and the ASI has them. There are very clear trends at various times of the year. It is interesting to me to look at certain key milestones in the year and the likelihood, or not, of hitting them.
Fair enough - the other feedback shows that there is clearly interest in these numbers.

If I might add my 2 cents, this type of data seems like it would benefit from a longer term analysis - maybe 5 days or a week - except perhaps in the case of very specific weather events where daily changes could be linked to ongoing events. Doing it on a daily basis without any specific events taking place it very much looks like cataloging noise in the extent data, not actual physical changes in the arctic. Even the 5-day averaged extent numbers fluctuate quite a bit above and below the average, even with a clear trend in place - logging the needed losses for being the record lowest etc on a daily basis doesn't seem to be linked to any physical reality.

However, this is just my 2 cents for consideration, since I started the sequence of offtopic posts in the first place - everybody is welcome to have a different opinion. Also sorry to gerontocrat for derailing the thread, I will stop now.

DavidR

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Re: 2019 sea ice area and extent data
« Reply #1896 on: July 30, 2019, 05:18:34 AM »
Attached is a graph showing cumulative losses from August 1st to the minimum.

Despite starting with a lower extent each decade, the area lost is increasing each decade. 
    ....

This is quite significant. For volume, anomaly charts suggest the trend leans opposite. (I haven't scrutinized the data, which appear highly variable by year.) If so, the combination implies a shrinking but resistant end-of-season blob over time.
I think latitude counts for a lot as the pack has shrunk.  It is also pulled North which means that the angle of incidence changes more rapidly and dramatically during the melt.  In short, while peak insulation is high, the timeframe is short, and what can practically be captured is less.

Lower latitude ice has longer timeframes to capture heat, and that capture over time will be more consistent.

At high latitude my hunch is increases in loss will be driven more by net increases in system heat over time, primarily imported from elsewhere.
Some time ago there was a post  suggesting a mathematical formula relating area loss and volume loss.  These must reach zero at approximately the same time so linear trends are unhelpful. According to the formula the last few million Km^2 of extent disappeared very quickly  as the volume declined.

We may have seen the start of this process in 2012 and we may see the process come into effect again this year.  Global Oceans, including the Arctic, have been warming up over the past seven years. It seems probable that there is a lot more heat in the Arctic than 7 years ago, so a much  less extreme weather event will be required to drive area and extent down to 2012 levels.   2019 is far enough ahead of 2012 at the moment that even the GAC may not significantly seperate them by Aug 10th.  (Another century drop on JAXA today putting 2019 further ahead of 2012 with 2012 losing less than 50K a day for the next  4 days)
« Last Edit: July 30, 2019, 05:40:25 AM by DavidR »
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Juan C. García

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Re: 2019 sea ice area and extent data
« Reply #1897 on: July 30, 2019, 05:46:26 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

July 29th, 2019:
     6,076,002 km2, a century drop of -114,081 km2.
     2019 is the lowest on record.
     (2012 highlighted).
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

bbr2314

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Re: 2019 sea ice area and extent data
« Reply #1898 on: July 30, 2019, 05:52:11 AM »
2012 plateaus for the next few days. We are now three days ahead of when 2012 hit this mark. This should ensure (IMO) that regardless of whether or not we get a GAC, we will be far below 2012 by 8/1, and will maintain distance through 8/10. I would guess we will see a departure of up to 300-400K KM^2 from 2012 at peak dissonance over the next few days.

gerontocrat

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Re: 2019 sea ice area and extent data
« Reply #1899 on: July 30, 2019, 06:24:55 AM »
JAXA ARCTIC EXTENT :- 6,076,002 km2(July 29, 2019)

On average, just over 3/4 of extent loss completed.

- Extent is lowest in the satellite record (42 days this year), extent is 127 k below 2012, 546 k below 2016.
- Extent loss on this day 114 k, 42 k more than the average loss on this day of 72 k.
- Extent loss from maximum 8,195 k, 578 k (7.6%) greater than the average of 7,618 k loss from maximum by this day,
- On average 77.1% of the melting season done, with 46 days to average date of minimum (13 September).

The Perils of Projections.
**Average remaining melt would give a minimum of 3.81 million km2, 2nd lowest in the satellite record, 0.63 million km2 above the 2012 low of 3.18 million km2 and 0.21 million below the 2nd lowest  in 2016 of 4.02 million km2.

Ice Melt Outlook The peak days of daily melt are past. From now to minimum, on average daily extent loss will initially slowly reduce, this reduction in daily loss gradually accelerating on the approach to minimum. 

A weather remark: Over the next 5 days Greenland, Baffin Bay and the CAA will still be warm, and at times hot. The CAA may well get some rain.

In the last 13 days the average extent loss per day has been just over 100k. The June volume data persuaded me to drop my guesstimate for the minimum  to below 4 million km2 from exactly 4 million km2. So far this seems to have been a sensible decision. Indeed, my June guess of 3.75 to 4.25 million km2 may be at risk, i.e. too high.

There is even a possibility that my July guess of 3.5 to 4 million km2 is also too high. This would require remaining melt to follow the pattern of 2016 at something like 15% above average.
______________________________________________________________
** For those unable to read table Arc1 attached, average remaining melt is the last 10 years average.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)