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Author Topic: Global sea ice area and extent data  (Read 108017 times)

gerontocrat

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Re: Global sea ice area and extent data
« Reply #600 on: July 03, 2019, 10:19:39 AM »
JAXA Global Sea Ice Extent as at 2 July 2019 :   22,678,822  km2

A 4 day run of extent losses towards the false minimum in Aug/Sep.

Global extent in 1st place, 15 k below 2017, and 1,012 k below 2018.

- extent loss on this day 42k, 29k different from the the average loss of 13 k on this day,
- extent gain from minimum to date is 6.43 million km2, 1.07 million km2 (14.3%) less than the average gain of 7.50 milllion km2 by this day,
-on average 83.1% of extent gain done and 127 days to maximum in early November.
 
But before the maximum, there is firstly a false maximum (in July). Indeed the average for the 2010's has this false max in the last week in June. Perhaps this year the false maximum has happened already?
For the next 2 and a bit months extent should fall until the false minimum (in early September),  before rising to the (usually) true maximum around the 4th of November.

The Perils of Projections
The last 10 years average remaining extent gain would give a maximum of 24.20 million km2,  0.57 million km2 more than the record low maximum in 2016 and 2nd lowest in the satellite record.

Volatility
2016
was unusual. From now on to the Arctic minimum, extent loss was not spectacular but above average. Antarctic sea ice gain to maximum was mostly below average. The result was that from now to November there was almost no increase in global sea ice compared with the average increase of 1.5 million km2.

In contrast the increase in global sea ice from now in 2006 was nearly 75%, 1.15 million km2 above the average.

A demonstration that combining two separate pieces of data makes volatility very high.
"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: Global sea ice area and extent data
« Reply #601 on: July 07, 2019, 09:34:33 AM »
JAXA Global Sea Ice Extent as at 6 July 2019 :    22,741,402  km2

A 4 day run of extent losses towards the false minimum in Aug/Sep was followed by 2 days of high gains and finally a day of a 0.5k loss..

Global extent in 1st place, 54 k below 2017, and 1,112 k below 2018.

- extent loss on this day 1k, 8k different from the the average gain of 7 k on this day,
- extent gain from minimum to date is 6.49 million km2, 0.97 million km2 (13.0%) less than the average gain of 7.47 milllion km2 by this day,
-on average 82.7% of extent gain done and 121 days to maximum in early November.
 
But before the maximum, there is firstly a false maximum (in July). Indeed the average for the 2010's has this false max in the last week in June. Perhaps this year the false maximum has happened already?
For the next 2 and a bit months extent should fall until the false minimum (in early September),  before rising to the (usually) true maximum around the 4th of November.

The Perils of Projections
The last 10 years average remaining extent gain would give a maximum of 24.30 million km2,  0.67 million km2 more than the record low maximum in 2016 and 2nd lowest in the satellite record.

Volatility
2016
was unusual. From now on to the Arctic minimum, extent loss was not spectacular but above average. Antarctic sea ice gain to maximum was mostly below average. The result was that from now to November there was a decrease in global sea ice extent compared with the average increase of 1.5 million km2.

In contrast the increase in global sea ice from now in 2006 was nearly 70% above the average.

A demonstration that combining two separate pieces of data makes volatility very high.
"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: Global sea ice area and extent data
« Reply #602 on: July 08, 2019, 07:35:30 AM »
The graphs show what happens with high Arctic extent loss and low Antarctic extent gain.
"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)

Tony Mcleod

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Re: Global sea ice area and extent data
« Reply #603 on: July 08, 2019, 11:23:42 AM »
"A demonstration that combining two separate pieces of data makes volatility very high."

I'm not sure it is. One of those separate pieces of data (the Arctic) is made up of a dozen or so separate pieces of data - the regions. I suspect volatility doesn't change much and if anything is reduced.

To balance out my pedantic pickiness I want to express my ongoing gratitude for your excellent analysis and reporting.  ;)

Stephan

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Re: Global sea ice area and extent data
« Reply #604 on: July 09, 2019, 06:45:21 PM »
JAXA arctic sea ice extent is now three days ahead of the 2010s average, and 12 days behind the Antarctic 2010s extent. This sums up to 15 days of more insulation, or more freezing energy that has to be released to reach the ice extent.
In comparison with the 2000s average the sum is higher (26 days), compared with the 1990s average the sum is 33 days. The highest difference results with the 1980s average (43 days).
These numbers matter, when it comes to the energy balance of our planet.

oren

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Re: Global sea ice area and extent data
« Reply #605 on: July 10, 2019, 03:14:59 AM »
JAXA arctic sea ice extent is now three days ahead of the 2010s average, and 12 days behind the Antarctic 2010s extent. This sums up to 15 days of more insulation, or more freezing energy that has to be released to reach the ice extent.
In comparison with the 2000s average the sum is higher (26 days), compared with the 1990s average the sum is 33 days. The highest difference results with the 1980s average (43 days).
These numbers matter, when it comes to the energy balance of our planet.
Returning to the problematic nature of summing two semi-related numbers, the Antarctic is currently in austral winter, hence the 12 days of insolation don't matter as much as it would seem. The 3 days are in boreal summer and matter a lot.

Stephan

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Re: Global sea ice area and extent data
« Reply #606 on: July 10, 2019, 09:07:53 PM »
I do think that also the lack of sea ice around Antarctica matters a lot. I am a layman, so please correct me if I'm wrong with my understanding.
As long as there are open waters (where used to be ice before) the temperature cannot drop too low. And when ice freezes, the freezing energy will be released into the waters below it and into the atmosphere. This also "saves" the area where it happens from becoming too cold. And in consequence the ice will be thinner than it used to be before 2015, and might be easier melted or broken up when the Austral summer starts...

oren

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Re: Global sea ice area and extent data
« Reply #607 on: July 10, 2019, 09:47:21 PM »
Of course Antarctic sea ice matters, I was just saying it is not additive in a simple way with the way Arctic sea ice matters.

gerontocrat

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Re: Global sea ice area and extent data
« Reply #608 on: July 14, 2019, 11:25:17 AM »
JAXA Global Sea Ice Extent as at 13 July 2019 :  22,726,409 km2

We are now in the period of extent losses towards the false minimum of late August / Early September

The overall picture for July sea ice so far is
- Antarctic sea ice gain more above than below average,
- Arctic sea ice loss more above than below average,
- Global extent more or less unchanged since 1 July.

Global extent in 1st place, 62 k below 2017, and 1,048 k below 2018.

- extent gain on this day 9k, 45k different from the the average loss of 36 k on this day,
- extent gain from minimum to date is 6.48 million km2, 0.87 million km2 (11.8%) less than the average gain of 7.34 milllion km2 by this day,
-on average 81.4% of extent gain done and 114 days to maximum in early November.
 
We should have passed the false maximum of early July.
For the next 2 months or a bit less extent should fall until the false minimum (in early September),  before rising to the (usually) true maximum around the 4th of November.

The Perils of Projections
The last 10 years average remaining extent gain would give a maximum of 24.40 million km2,  0.76 million km2 more than the record low maximum in 2016 and 2nd lowest in the satellite record.
"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: Global sea ice area and extent data
« Reply #609 on: July 16, 2019, 06:13:09 AM »
Low Arctic extent loss and high Antarctic extent gains.
"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)

Stephan

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Re: Global sea ice area and extent data
« Reply #610 on: July 16, 2019, 06:43:05 PM »
On July 14 for the first time since March 28 the difference of global SIE to the 2000s average is below 2 M kmĀ²