Support the Arctic Sea Ice Forum and Blog

Author Topic: 2018 sea ice area and extent data  (Read 573320 times)

Steven

  • Grease ice
  • Posts: 617
    • View Profile
  • Liked: 194
  • Likes Given: 17
Re: 2018 sea ice area and extent data
« Reply #1450 on: August 19, 2018, 01:53:19 PM »
NSIDC sea ice area is currently 9th lowest for the date:


gerontocrat

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1451 on: August 19, 2018, 05:49:30 PM »
NSIDC Total Area as at 18 August (5 day trailing average) =   3,846,590 km2
This is now 179 k above the 2010-2017 average total area for this date


Total Area loss 73 K ,

Central Seas loss         68 k,
Peripheral Seas loss       3 k, all seas at or near zero area.
Other Seas gain             2 k. all seas at or near zero area.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 3 k, area 80 k, below the 2010's average - just.
Atlantic Side
- Baffin Sea loss 0 k, area 28 k - almost done,
- Greenland Sea loss 3 k, area 58k,
- Barents Sea - finished,
- The Kara Sea area loss 0 k, area is now 28 k, well under 5% of 1980's average maximum.
- The Laptev Sea area loss 3 k, area 44 k, 5% of maximum.

CAB
- Beaufort Sea loss 6 k,
- The Canadian Archipelago loss 10 k,
- East Siberian Sea loss 28 k .
- The Central Arctic Sea loss 18 k,

Other seas

- St Lawrence -finished,
- Hudson Bay area loss 2 k, Area now 31 k,
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply  But the area loss of 73 k is above this day's 2010's average by about 25 k. Extent loss (also 5-day trailing average)) was down to 51k, about average for the day. And daily extent loss was a mere 10k  after 24k and 5k the days before. This probably means that area losses will see a sharp fall in the coming days, but of course could then turn around to high losses again.

It is all about the 4 central seas now. The melting season ain't over yet, there is a chorus of fat ladies waiting in the wings for a chance to sing.
"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)

Hautbois

  • New ice
  • Posts: 33
    • View Profile
  • Liked: 44
  • Likes Given: 0
Re: 2018 sea ice area and extent data
« Reply #1452 on: August 19, 2018, 10:10:10 PM »
The latest thrilling instalment of my 2018 JAXA minimum running back graph, featuring SEVEN new dots!

It reminds me somewhat of this   

Juan C. García

  • Nilas ice
  • Posts: 1942
    • View Profile
  • Liked: 954
  • Likes Given: 639
Re: 2018 sea ice area and extent data
« Reply #1453 on: August 20, 2018, 06:00:37 AM »
[ADS-NIPR-JAXA] ASI Extent.

August 19th, 2018: 5,148,707 km2, a drop of -36,632 km2.
2018 is the sixth lowest on record.
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.

Wherestheice

  • Frazil ice
  • Posts: 313
    • View Profile
  • Liked: 89
  • Likes Given: 19
Re: 2018 sea ice area and extent data
« Reply #1454 on: August 20, 2018, 06:22:17 AM »
I wonder why there has been a slowdown in melt
"When the ice goes..... F***

Rod

  • Frazil ice
  • Posts: 427
    • View Profile
  • Liked: 300
  • Likes Given: 13
Re: 2018 sea ice area and extent data
« Reply #1455 on: August 20, 2018, 07:47:40 AM »
I wonder why there has been a slowdown in melt

Melt and extent are two very different things.  I don't mean this as a shot against you because I always appreciate your comments Wheresheice! But, it is always important to understand what the data represents and how the data was collected. 

Sometimes people on this forum look at number lines representing data points, and jump to conclusions without any real understanding about what the data points represent.   

Extent tells you where the ice is, but it does not tell you how much ice is there.  Extent is an all or nothing proposition with an 85% margin of error over each grid cell.  The extent numbers might or might not indicate whether ice is melting.

 

gerontocrat

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1456 on: August 20, 2018, 08:10:23 AM »
JAXA ARCTIC EXTENT 5,148,707 km2(August 19, 2018)

Just to add to Juan's post...

- Extent is now just 21 k km2  (0.4 %) below the 2010's average extent on this date,
- and 56 k (1.1%) above 2017 (which is in a series of below average extent losses) ,
- Extent loss to date is now 355k km2 (3.9 %) below the 2008-2017 average, with 91.3 % of the average melting season done.

Resulting minimum from average remaining melt is  4.28 million km2. Range of results from last ten years remaining melt is 4.10 to 4.53 million km2 - also a narrowing range. For a minimum at 2nd lowest remaining melt needs to be about 25% above average, very unlikely. For a new record low remaining melt would need to be 1.97 million km2 as opposed to the average remaining melt of 0.83 million km2, i.e 1.09 million (128 %) above the average. Impossible.

Of interest (?) is that in 2012 melt from this point was just 0.19 million (21%) above the average remaining melt.

That 2017 feeling wanes and waxes- just when it looks like the melting has some legs it slows again. There is, on average, under 9% (24 days) of further extent loss to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss do a 2017 and sharply reduce? Yes.

A September minimum in the range of 4.00 to 4.50 million km2 seems probable, with the result of least drama at 0.2 million km2 above 2nd place, 0.2 million km2 below 2017 and about 1 million km2 above the 2012 outlier.
"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)

Wherestheice

  • Frazil ice
  • Posts: 313
    • View Profile
  • Liked: 89
  • Likes Given: 19
Re: 2018 sea ice area and extent data
« Reply #1457 on: August 20, 2018, 08:37:19 AM »
I wonder why there has been a slowdown in melt

Melt and extent are two very different things.  I don't mean this as a shot against you because I always appreciate your comments Wheresheice! But, it is always important to understand what the data represents and how the data was collected. 

Sometimes people on this forum look at number lines representing data points, and jump to conclusions without any real understanding about what the data points represent.   

Extent tells you where the ice is, but it does not tell you how much ice is there.  Extent is an all or nothing proposition with an 85% margin of error over each grid cell.  The extent numbers might or might not indicate whether ice is melting.

Thank you for responding! I should have said loss of extent, that’s what I was trying to get at lol. I need sleep. But yes thank you for clearing that up. What I’m really trying to understand is why have the last 3 days only lost around 30-40 k km2. It seems a lot less than normal, but this is probably just normal fluctuations right?
"When the ice goes..... F***

Rod

  • Frazil ice
  • Posts: 427
    • View Profile
  • Liked: 300
  • Likes Given: 13
Re: 2018 sea ice area and extent data
« Reply #1458 on: August 20, 2018, 08:48:54 AM »
I think you are right.  There has been some dispersion to mask extent losses, but it has not been huge. 

In my mind, I'm amazed at how well the ice in the ESS has held up to all the sunshine this month. The models predicted it was very thick and they seem to have been right.  However, that ice seems to be streatched pretty thin right now. 

We could see some really big extent losses coming soon.  But, it is also getting late in the season so maybe that thin ice will hold up.  No one knows.  That is why we all watch worldview with baited breath and then come on here to voice our comments and concerns. 




binntho

  • Nilas ice
  • Posts: 1382
    • View Profile
  • Liked: 458
  • Likes Given: 106
Re: 2018 sea ice area and extent data
« Reply #1459 on: August 20, 2018, 09:38:24 AM »
What I’m really trying to understand is why have the last 3 days only lost around 30-40 k km2. It seems a lot less than normal, but this is probably just normal fluctuations right?

I noticed in one of A-Teams great animations that the Svalbard - Franz Josef Land ice front had moved southwards a bit - not by much, but it's a long front. And the wind is strongly from the north in the Fram Strait at the moment. So an increase in extent on that side could be dampening any reduction in extent happening elsewhere.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

Wherestheice

  • Frazil ice
  • Posts: 313
    • View Profile
  • Liked: 89
  • Likes Given: 19
Re: 2018 sea ice area and extent data
« Reply #1460 on: August 20, 2018, 09:53:44 AM »
What I’m really trying to understand is why have the last 3 days only lost around 30-40 k km2. It seems a lot less than normal, but this is probably just normal fluctuations right?

I noticed in one of A-Teams great animations that the Svalbard - Franz Josef Land ice front had moved southwards a bit - not by much, but it's a long front. And the wind is strongly from the north in the Fram Strait at the moment. So an increase in extent on that side could be dampening any reduction in extent happening elsewhere.

Yeah thats true
"When the ice goes..... F***

Ned W

  • Guest
Re: 2018 sea ice area and extent data
« Reply #1461 on: August 20, 2018, 01:31:44 PM »
I wonder why there has been a slowdown in melt
JAXA extent has had three days of slightly-below average decreases, but they were preceded by three days of slightly-above average decreases.  The net total over six days:

Average (2007-2017): -57.6 K extent loss per day
2018:  -57.1 K extent loss per day

So things are actually proceeding rather unremarkably

Here are the predict-o-matic probabilities for JAXA daily minimum:



And here are the probabilities for rankings.  There's about an 80% chance that 2018 will end up in either 6th or 4th place:



After those two, the next most likely possibility is 8th place, but it's only a 6% chance, and it goes downhill from there.

And here's the time-evolution chart for 2018's minimum, with the 95% prediction interval:


gerontocrat

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1462 on: August 20, 2018, 02:25:10 PM »
NSIDC Total Area as at 19 August (5 day trailing average) =   3,796,960    km2
This is 179 k above the 2010-2017 average total area for this date


Total Area loss 50 K ,

Central Seas loss         48 k,
Peripheral Seas loss       2 k, all seas at or near zero area.
Other Seas gain/loss      0 k all seas at or near zero area.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 4 k, area 76 k, below the 2010's average - just.
Atlantic Side
- Baffin Sea loss 0 k, area 28 k - almost done,
- Greenland Sea loss 2 k, area 56k,
- Barents Sea - finished,
- The Kara Sea area gain 1 k, area is now 29 k, well under 5% of 1980's average maximum.
- The Laptev Sea area loss 1 k, area 44 k, 5% of maximum.

CAB
- Beaufort Sea loss 4 k,
- The Canadian Archipelago loss 7 k,
- East Siberian Sea loss 13 k .
- The Central Arctic Sea loss 21 k,

Other seas

- St Lawrence -finished,
- Hudson Bay area gain 0.5 k, Area now 32 k,
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply  The area loss of 50 k is average for this day. Extent loss (also 5-day trailing average)) was down to 27k, well below average for the day. And daily extent loss was a mere  12 k, after 10k,  24k, and 5k the days before. This probably means that 5-day average area losses will see a sharp fall in the coming days, but of course could then turn around to high losses again (or not).

It is all about the 4 central seas now. The melting season ain't over yet, there is a chorus of fat ladies waiting in the wings for a chance to sing, but I think one just left.
"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)

RoxTheGeologist

  • Grease ice
  • Posts: 501
    • View Profile
  • Liked: 150
  • Likes Given: 112
Re: 2018 sea ice area and extent data
« Reply #1463 on: August 20, 2018, 05:48:47 PM »

In my mind, I'm amazed at how well the ice in the ESS has held up to all the sunshine this month. The models predicted it was very thick and they seem to have been right.  However, that ice seems to be stretched pretty thin right now. 


It surprised me too: I thought there would have been a lot of extra heat insolated into the neighboring seas with the early opening of the Chukchi and the Laptev, but if there is extra energy the heat hasn't been mixed into the ESS as yet. It's a very interesting melt season.

Pmt111500

  • Nilas ice
  • Posts: 2196
  • Yes, I do not always bicycle
    • View Profile
  • Liked: 197
  • Likes Given: 137
Re: 2018 sea ice area and extent data
« Reply #1464 on: August 20, 2018, 09:20:02 PM »

In my mind, I'm amazed at how well the ice in the ESS has held up to all the sunshine this month. The models predicted it was very thick and they seem to have been right.  However, that ice seems to be stretched pretty thin right now. 


It surprised me too: I thought there would have been a lot of extra heat insolated into the neighboring seas with the early opening of the Chukchi and the Laptev, but if there is extra energy the heat hasn't been mixed into the ESS as yet. It's a very interesting melt season.
Yes, this has surprised me too on several years and did it again. I'm beginning to think the ocean might be extra cold here fir some reason.
Cooling the outside by heat pump.

Juan C. García

  • Nilas ice
  • Posts: 1942
    • View Profile
  • Liked: 954
  • Likes Given: 639
Re: 2018 sea ice area and extent data
« Reply #1465 on: August 21, 2018, 05:58:19 AM »
[ADS-NIPR-JAXA] ASI Extent.

August 20th, 2018: 5,082,310 km2, a drop of -66,397 km2.
2018 is the sixth lowest on record.
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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1466 on: August 21, 2018, 07:52:10 AM »
JAXA ARCTIC EXTENT 5,082,310 km2(August 20, 2018)

Just to add to Juan's post...

- Extent is now just 40 k km2  (0.8 %) below the 2010's average extent on this date,
- and 24 k (0.5 %) above 2017 (which is in a series of below average extent losses) ,
- Extent loss to date is now 336k km2 (3.7 %) below the 2008-2017 average, with 91.8 % of the average melting season done.

Resulting minimum from average remaining melt is  4.26 million km2. Range of results from last ten years remaining melt is 4.08 to 4.50 million km2 - a narrowing range. For a minimum at 2nd lowest remaining melt needs to be about 24% above average, very unlikely. For a new record low remaining melt would need to be 1.90 million km2 as opposed to the average remaining melt of 0.82 million km2, i.e 1.08 million (133 %) above the average. Impossible.

Of interest (?) is that in 2012 melt from this point was just 0.15 million (18%) above the average remaining melt.

That 2017 feeling wanes and waxes- just when it looks like the melting has some legs it slows again and vice-versa. There is, on average, under 9% (23 days) of further extent loss to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss do a 2017 and sharply reduce? Yes.

A September minimum in the range of 4.00 to 4.50 million km2 seems probable , with the result of least drama at 4th place - 0.15 million km2 above 2nd place, 0.25  million km2 below 2017 and approaching 1 million km2 above the 2012 outlier.
"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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1467 on: August 21, 2018, 02:42:52 PM »
NSIDC Total Area as at 20 August (5 day trailing average) =   3,757,691 km2
This is 181 k above the 2010-2017 average total area for this date


Total Area loss 39 K ,

Central Seas loss         37 k,
Peripheral Seas loss       1 k, all seas at or near zero area.
Other Seas gain/loss      1 k all seas at or near zero area.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 3 k, area 73 k, below the 2010's average - just.
Atlantic Side
- Baffin Sea loss 0 k, area 28 k - almost done,
- Greenland Sea loss 2 k, area 54k,
- Barents Sea - finished,
- The Kara Sea area loss 3 k, area is now 26 k, well under 5% of 1980's average maximum.
- The Laptev Sea area loss 2 k, area 42 k, <5% of maximum.

CAB
- Beaufort Sea loss 7 k,
- The Canadian Archipelago loss 6 k,
- East Siberian Sea gain 3 k .
- The Central Arctic Sea loss 19 k,

Other seas

- St Lawrence -finished,
- Hudson Bay area loss 1 k, Area now 31 k, Foxe basin ice hanging on.
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 39 k is just below average for this day. Extent loss (also 5-day trailing average)) was up at 38k, below average for the day. But daily extent loss was an impressive 139k after a series of very low losses - 12 k, 10k,  24k, and 5k the days before.

It is all about the 4 central seas now. The melting season ain't over yet, there is a chorus of fat ladies waiting in the wings for a chance to sing, but I think one just left, or did she come back again.
"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)

Shared Humanity

  • Guest
Re: 2018 sea ice area and extent data
« Reply #1468 on: August 21, 2018, 03:23:44 PM »
JAXA ARCTIC EXTENT 5,082,310 km2(August 20, 2018)

Just to add to Juan's post...

Thank you for these posts. That daily extent gain/extent loss chart sure appears predictive. I love your data based analysis.

gerontocrat

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1469 on: August 21, 2018, 03:40:11 PM »
But data has its limitations.

NSIDC data says the Kara Sea Area has been at record lows for the day for 14 days in a row since 7th August, and area is shown at 26k. (as in the graph attached))

But is the actual area Zero? NSIDC's resolution is to 625 km2 squares, AMSR2 to 100 km2 squares. The Univ Bremen AMSR2 image says no ice in the Ob eustary- the NSIDC image says there is.

26K ? Pretty meaningless in the grand scheme of things, but the record of changes over the years in ice-free days in that part of the Arctic in absolute terms  may be wrong (though correct in trends).

ps: Maybe NSIDC exaggerates ice area in Foxe basin as well.
"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)

oren

  • Moderator
  • First-year ice
  • Posts: 5859
    • View Profile
  • Liked: 2006
  • Likes Given: 1745
Re: 2018 sea ice area and extent data
« Reply #1470 on: August 21, 2018, 04:17:39 PM »
gerontocrat, of course NSIDC is exaggerating due to its limitations. But by how much? Luckily UH and Wipneus have the answers. Note UH's grid size is 3.125x3.125 or 9.77 km2, so a factor of 10 smaller than JAXA and Bremen's 10x10 km2, and a factor of 64 smaller than NSIDC.
Kara Sea has a remaining area of 2k km2, and Hudson Bay 19k km2. Even this may sometimes include phantom ice, but the problem is inherently much less prevalent.

https://sites.google.com/site/arctischepinguin/home/amsr2/data/UH_AMSR2_3.125km_Area_Extent-v0.0.txt?attredirects=0&d=1

gerontocrat

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1471 on: August 21, 2018, 04:29:18 PM »
gerontocrat, of course NSIDC is exaggerating due to its limitations. But by how much? Luckily UH and Wipneus have the answers. Note UH's grid size is 3.125x3.125 or 9.77 km2, so a factor of 10 smaller than JAXA and Bremen's 10x10 km2, and a factor of 64 smaller than NSIDC.
Kara Sea has a remaining area of 2k km2, and Hudson Bay 19k km2. Even this may sometimes include phantom ice, but the problem is inherently much less prevalent.


But what to do about recording trends in individual seas going back to 1979 based on NSIDC data? Consistency cannot be allowed to be broken even though Wipneus's data is so much better.

I think one has to live with this deficiency but add the caveat to any conclusions / tables and graphs of trends, just like one lives with the pole hole of 3 different dimensions over the years.

Ho hum. Only ??? is perfect.
"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)

oren

  • Moderator
  • First-year ice
  • Posts: 5859
    • View Profile
  • Liked: 2006
  • Likes Given: 1745
Re: 2018 sea ice area and extent data
« Reply #1472 on: August 21, 2018, 06:02:33 PM »
I agree, for comparison and historical trends NSIDC are doing just fine (love your frequent charts btw). But when I want to know where the ice really is, UH delivers the best results.

Pmt111500

  • Nilas ice
  • Posts: 2196
  • Yes, I do not always bicycle
    • View Profile
  • Liked: 197
  • Likes Given: 137
Re: 2018 sea ice area and extent data
« Reply #1473 on: August 21, 2018, 06:13:46 PM »
Foxe basin is the recipient of much ice during early melt. The passage towards northern archipelago is almost one-way, so it's no wonder there are some thick floes resisting melt for long in the summer
Cooling the outside by heat pump.

magnamentis

  • Guest
Re: 2018 sea ice area and extent data
« Reply #1474 on: August 21, 2018, 10:10:01 PM »
Foxe basin is the recipient of much ice during early melt. The passage towards northern archipelago is almost one-way, so it's no wonder there are some thick floes resisting melt for long in the summer

true that, the so called accelerating garlic press that indicates kind of increased ice export also measn what you say, thicker ice inside the nooks and crannies of the archipelago that slows down that export for some time as well as it does and will reduce melting speed for a certain time which is probably one of the reasons why despite very low ice minimums the NWP did not open significantly early or wider.

i'm not sure but one could see this as kind of a feedback.

Juan C. García

  • Nilas ice
  • Posts: 1942
    • View Profile
  • Liked: 954
  • Likes Given: 639
Re: 2018 sea ice area and extent data
« Reply #1475 on: August 22, 2018, 05:51:45 AM »
[ADS-NIPR-JAXA] ASI Extent.

August 21st, 2018: 5,022,611 km2, a drop of -59,699 km2.
2018 is the fifth lowest on record.
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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1476 on: August 22, 2018, 07:23:22 AM »
JAXA ARCTIC EXTENT  5,022,611 km2(August 21, 2018)

Just to add to Juan's post...

- Extent is now 58 k km2  (1.2 %) below the 2010's average extent on this date,
- and 25 k (0.5 %) below 2017 (which is in a series of below average extent losses),
- Extent loss to date is now 318k km2 (3.5 %) below the 2008-2017 average, with 92.2 % of the average melting season done.

Resulting minimum from average remaining melt is  4.25 million km2. Range of results from last ten years remaining melt is 4.06 to 4.45 million km2 - a narrowing range. For a minimum at 2nd lowest remaining melt needs to be about 23% above average, very unlikely. For a new record low remaining melt would need to be 138 % above the average. Impossible.

Of interest (?) is that in 2012 melt from this point was just 0.12 million (15%) above the average remaining melt.

That 2017 feeling wanes and waxes- just when it looks like the melting has some legs it slows again and vice-versa. There is, on average, under 8% (22 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss do a 2017 and sharply reduce? Yes.

A September minimum in the range of 4.00 to 4.50 million km2 seems probable , with the result of least drama at 4th place - 0.15 million km2 above 2nd place, 0.25  million km2 below 2017 and approaching 1 million km2 above the 2012 outlier.
"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)

lurkalot

  • New ice
  • Posts: 30
    • View Profile
  • Liked: 2
  • Likes Given: 0
Re: 2018 sea ice area and extent data
« Reply #1477 on: August 22, 2018, 02:08:20 PM »
I think your chart may have the extent figures for 2010 and 2011 the wrong way round, Gerontocrat. Thank you for all your posts.

ArcticMelt1

  • New ice
  • Posts: 77
    • View Profile
  • Liked: 15
  • Likes Given: 1
Re: 2018 sea ice area and extent data
« Reply #1478 on: August 22, 2018, 02:11:08 PM »
https://twitter.com/zlabe

Quote
Sea ice extent on the Atlantic side of the #Arctic has reached a new all-time record low for the region (combined Barents-Kara-Greenland Seas). Each line shows one year from 1979 (purple) to 2017 (white). The previous record was just last year.

[Daily data is from the @NSIDC]


ArcticMelt1

  • New ice
  • Posts: 77
    • View Profile
  • Liked: 15
  • Likes Given: 1
Re: 2018 sea ice area and extent data
« Reply #1479 on: August 22, 2018, 02:16:08 PM »
This year set a 465-year record!

https://link.springer.com/article/10.1007/s00300-014-1482-1
Quote
The position of the ice edge (the gray vertical bars) in August between Svalbard and Franz Josef Land for the period 1553–2012, given as the mean latitude within the sector 20–45°E (modified after Vinje 1999 and updated to summer 2012).



Who else doubts global warming?

ArcticMelt1

  • New ice
  • Posts: 77
    • View Profile
  • Liked: 15
  • Likes Given: 1
Re: 2018 sea ice area and extent data
« Reply #1480 on: August 22, 2018, 02:22:38 PM »
Now this figure is more than 83 degrees north latitude.

ArcticMelt1

  • New ice
  • Posts: 77
    • View Profile
  • Liked: 15
  • Likes Given: 1
Re: 2018 sea ice area and extent data
« Reply #1481 on: August 22, 2018, 02:25:55 PM »
Other record charts.

gerontocrat

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1482 on: August 22, 2018, 03:06:16 PM »
NSIDC Total Area as at 21 August (5 day trailing average) = 3,724,809  km2
This is 186 k above the 2010-2017 average total area for this date


Total Area loss 33 K ,

Central Seas loss         27 k,
Peripheral Seas loss       2 k, all seas at or near zero area.
Other Seas gain/loss      4 k all seas at or near zero area.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 2 k, area 71 k, at the 2010's average - just.
Atlantic Side
- Baffin Sea loss 0 k, area 28 k - almost done,
- Greenland Sea loss 2 k, area 52k,
- Barents Sea - finished,
- The Kara Sea area loss 1 k, area is now 25 k, well under 5% of 1980's average maximum.
- The Laptev Sea area loss 3 k, area 39 k, <5% of maximum.

CAB
- Beaufort Sea loss 0 k,
- The Canadian Archipelago loss 2 k,
- East Siberian Sea gain 5 k .
- The Central Arctic Sea loss 24 k,

Other seas

- St Lawrence -finished,
- Hudson Bay area loss 4 k, Area now 27 k, Foxe basin ice hanging on.
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 33 k is below average by 5k for this day. Extent loss (also 5-day trailing average)) was up at 55k, aboveaverage for the day. But daily extent loss was 87k after an impressive 139k and before a series of very low losses - 12 k, 10k,  24k, and 5k the days before. End of season wobbles.

It is all about the 4 central seas now. The melting season ain't over yet, there is a chorus of fat ladies waiting in the wings for a chance to sing, but I think one just left, or did she come back again, and left again..

ps: Laptev area loss still going down. Seems to be part of that Atlantic front highlighted by Zlabe.
« Last Edit: August 22, 2018, 03:11:24 PM by gerontocrat »
"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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1483 on: August 22, 2018, 06:06:17 PM »
I think your chart may have the extent figures for 2010 and 2011 the wrong way round, Gerontocrat. Thank you for all your posts.
Well spotted.

perhaps I should lurk a bit more before rushing into print.
"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

  • Nilas ice
  • Posts: 1287
    • View Profile
  • Liked: 536
  • Likes Given: 222
Re: 2018 sea ice area and extent data
« Reply #1484 on: August 22, 2018, 06:46:21 PM »
Gerontocrat,
I have a proposal for you: Would you mind to add a line into your table below the individual seas' names with their area? So it would be easier to check the rough percentage of ice coverage. Thank you.
It is too late just to be concerned about Climate Change

Alison

  • New ice
  • Posts: 51
    • View Profile
  • Liked: 22
  • Likes Given: 141
Re: 2018 sea ice area and extent data
« Reply #1485 on: August 23, 2018, 04:07:51 AM »
Quote
Gerontocrat. Thank you for all your posts.

I’d like to second that - although I’m not able to add much to this topic, I read your posts every day!

Juan C. García

  • Nilas ice
  • Posts: 1942
    • View Profile
  • Liked: 954
  • Likes Given: 639
Re: 2018 sea ice area and extent data
« Reply #1486 on: August 23, 2018, 06:02:01 AM »
[ADS-NIPR-JAXA] ASI Extent.

August 22nd, 2018: 4,975,271 km2, a drop of -47,340 km2.
2018 is the fifth lowest on record.
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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1487 on: August 23, 2018, 08:03:44 AM »
JAXA ARCTIC EXTENT  4,975,271 km2(August 22, 2018)

Just to add to Juan's post...
- There was one vote for above 5 million km2 in the August JAXA SIE poll - sorry,
- Extent is now 48 k km2  (1.0 %) below the 2010's average extent on this date,
- and 28 k (0.6 %) below 2017 (which is in a series of below average extent losses),
- Extent loss to date is now 331k km2 (3.6 %) below the 2008-2017 average, with 92.8 % of the average melting season done.

Resulting minimum from average remaining melt is  4.26 million km2. Range of results from last ten years remaining melt is 4.08 to 4.44 million km2 - a narrowing range.

That 2017 feeling wanes and waxes- just when it looks like the melting has some legs it slows again and vice-versa. There is, on average, under 8% (21 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss do a 2017 and sharply reduce? Yes.

A September minimum in the range of 4.00 to 4.50 million km2 seems probable, with the result of least drama at 4th place - 0.15 million km2 above 2nd place, 0.25  million km2 below 2017 and approaching 1 million km2 above the 2012 outlier.
"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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1488 on: August 23, 2018, 02:02:56 PM »
Gerontocrat,
I have a proposal for you: Would you mind to add a line into your table below the individual seas' names with their area? So it would be easier to check the rough percentage of ice coverage. Thank you.
I will have a think about that - will be looking at what I produce after this melting season ends.
"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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1489 on: August 23, 2018, 02:15:00 PM »
NSIDC Total Area as at 22 August (5 day trailing average) = 3,673,934  km2
This is 167 k above the 2010-2017 average total area for this date


Total Area loss 51 K ,

Central Seas loss         49 k,
Peripheral Seas loss       0 k, all seas at or near zero area.
Other Seas gain/loss      2 k all seas at or near zero area.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 1 k, area 70 k, now above 2010's average - just.
Atlantic Side
- Baffin Sea loss 0 k, area 28 k - almost done,
- Greenland Sea gain 1 k, area 53k,
- Barents Sea - finished,
- The Kara Sea area loss 0 k, area is now 25 k, well under 5% of 1980's average maximum.
- The Laptev Sea area loss 4 k, area 35 k, <5% of maximum.

CAB
- Beaufort Sea loss 1 k,
- The Canadian Archipelago loss 1 k,
- East Siberian Sea loss 7 k .
- The Central Arctic Sea loss 34 k,

Other seas

- St Lawrence -finished,
- Hudson Bay area loss 2 k, Area now 24 k.
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 51 k is above average by about 15k for this day. Extent loss (also 5-day trailing average)) was up at 56k, above average for the day. But daily extent loss was 34k, c.f. 87k, 139k, 12 k and 10k the days before. End of season wobbles. About 3 weeks to go.

It is all about the 4 central seas now. The melting season ain't over yet, there is a chorus of fat ladies waiting in the wings for a chance to sing, but I think one just left, or did she come back again, and left again..

ps: Laptev area loss still going down. Seems to be part of that Atlantic front highlighted by Zlabe.
[/quote]
"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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1490 on: August 23, 2018, 03:22:54 PM »
Here are the area graphs for the 4 seas that matter most.
"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

  • Nilas ice
  • Posts: 1942
    • View Profile
  • Liked: 954
  • Likes Given: 639
Re: 2018 sea ice area and extent data
« Reply #1491 on: August 24, 2018, 05:49:40 AM »
[ADS-NIPR-JAXA] ASI Extent.

August 23rd, 2018: 4,945,395 km2, a drop of -29,876 km2.
2018 is the sixth lowest on record.
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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1492 on: August 24, 2018, 09:26:32 AM »
JAXA ARCTIC EXTENT  4,945,395 km2(August 23, 2018)

Just to add to Juan's post...
- Extent is now a mere 22 k km2  (0.5 %) below the 2010's average extent on this date,
- and 3 k (0.0 %) above 2017 (which is in a series of below average extent losses),
- Extent loss to date is now 358k km2 (3.8 %) below the 2008-2017 average, with 93.4 % of the average melting season done.

Resulting minimum from average remaining melt is  4.29 million km2. Range of results from last ten years remaining melt is 4.11 to 4.47 million km2 - a narrowing range.

That 2017 feeling wanes and waxes- just when it looks like the melting has some legs it slows again and vice-versa. There is, on average, under 7% (20 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss do a 2017 and sharply reduce? Yes.

A September minimum in the range of 4.00 to 4.50 million km2 seems probable, with the result of least drama at 4th place - 0.15 million km2 above 2nd place, 0.25  million km2 below 2017 and approaching 1 million km2 above the 2012 outlier.

It also seems highly probable that the data will show that melt was below average, considerably so, and therefore it could be said that only the very low March '18 winter maximum prevented the 2018 minimum from being considerably higher.
"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)

oren

  • Moderator
  • First-year ice
  • Posts: 5859
    • View Profile
  • Liked: 2006
  • Likes Given: 1745
Re: 2018 sea ice area and extent data
« Reply #1493 on: August 24, 2018, 10:52:02 AM »
It also seems highly probable that the data will show that melt was below average, considerably so, and therefore it could be said that only the very low March '18 winter maximum prevented the 2018 minimum from being considerably higher.
Of course, this is a chicken and egg issue. It could be said the very low winter maximum prevented above-average melt, as the ice to melt was already non-existent.

gerontocrat

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1494 on: August 24, 2018, 12:10:07 PM »
It also seems highly probable that the data will show that melt was below average, considerably so, and therefore it could be said that only the very low March '18 winter maximum prevented the 2018 minimum from being considerably higher.
Of course, this is a chicken and egg issue. It could be said the very low winter maximum prevented above-average melt, as the ice to melt was already non-existent.
I was sure someone would come back with that - and, of course, that raises the question - does low winter sea ice freeze tend to promote or tend to retard further summer melt, which in turn leads us off-topic and to move to Tony's infamous "Stupid" question concerning the impact of an ice-free summer arctic.

EDIT: Much of the Bering Sea did not freeze up last winter (maxed at < 50% of average). This summer, melt came on time early and the sea was virtually ice-free well over a month ahead of schedule. This, at least in one sea in one instance, contradicts the speculation that a low winter maximum tends to reduce melt in the following season.
« Last Edit: August 24, 2018, 12:33:25 PM by gerontocrat »
"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)

oren

  • Moderator
  • First-year ice
  • Posts: 5859
    • View Profile
  • Liked: 2006
  • Likes Given: 1745
Re: 2018 sea ice area and extent data
« Reply #1495 on: August 24, 2018, 01:47:55 PM »
And the nagging voice continues:  :P
Total Bering melt in 2012 was 500k km2. This year it was only 200k km2. A low melt year? No, a poor freeze year...

gerontocrat

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1496 on: August 24, 2018, 02:26:52 PM »
And the nagging voice continues:  :P
Total Bering melt in 2012 was 500k km2. This year it was only 200k km2. A low melt year? No, a poor freeze year...
Lies, damned lies, and statistics. But there was only 200k left to freeze. If there was more ice left than that then that would have melted as well, or would it. This could go on forever - unlike the ice.
"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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1497 on: August 24, 2018, 02:39:26 PM »
NSIDC Total Area as at 23 August (5 day trailing average) = 3,631,791  km2
This is 147 k above the 2010-2017 average total area for this date


Total Area loss 42 K ,

Central Seas loss         43 k,
Peripheral Seas loss       1 k, all seas at or near zero area.
Other Seas gain             2 k all seas at or near zero area.

Analysis of individual seas.
Pacific Side
- The Bering Sea - finished,
- Chukchi Sea loss 3 k, area 67 k, now above 2010's average.
Atlantic Side
- Baffin Sea loss 0 k, area 28 k - almost done,
- Greenland Sea loss 1 k, area 5k,
- Barents Sea - finished,
- The Kara Sea area loss 0 k, area is now 24 k, < 5% of 1980's average maximum.
- The Laptev Sea area loss 3 k, area 32 k, <5% of maximum.

CAB
- Beaufort Sea loss  0 k,
- The Canadian Archipelago loss 0 k,
- East Siberian Sea loss 14 k .
- The Central Arctic Sea loss 22 k,

Other seas

- St Lawrence -finished,
- Hudson Bay area gain 2 k, Area now 26 k
- The Okhotsk Sea - finished.

On average, this is when daily area loss declines sharply and wobbles from day to day. The area loss of 41 k is above average by about 20k for this day. Extent loss (also 5-day trailing average)) was 44k, below average for the day. But daily extent gained 54k, c.f. losses of 34k,  87k, 139k, and 12 k the days before. End of season wobbles. About 3 weeks or less to go.

It is all about the 4 (?) central seas now. At the moment Beaufort and the CAA have stalled. Is it now just about the ESS and the Central Arctic Sea? The melting season ain't over yet, there is a chorus of fat ladies waiting in the wings for a chance to sing, but I think two just left.....

"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

  • Nilas ice
  • Posts: 1942
    • View Profile
  • Liked: 954
  • Likes Given: 639
Re: 2018 sea ice area and extent data
« Reply #1498 on: August 25, 2018, 05:53:55 AM »
[ADS-NIPR-JAXA] ASI Extent.

August 24th, 2018: 4,904,571 km2, a drop of -40,824 km2.
2018 is the sixth lowest on record.
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

  • First-year ice
  • Posts: 8661
    • View Profile
  • Liked: 3405
  • Likes Given: 25
Re: 2018 sea ice area and extent data
« Reply #1499 on: August 25, 2018, 06:09:37 AM »
JAXA ARCTIC EXTENT  4,904,571 km2(August 24, 2018)

Just to add to Juan's post...
- Extent is now a mere 9 k km2  (0.2 %) below the 2010's average extent on this date,
- and 11 k (0.2 %) above 2017,
- Extent loss to date is now 376 k km2 (4.0 %) below the 2008-2017 average, with 94 % of the average melting season done.

Resulting minimum from average remaining melt is  4.30 million km2. Range of results from last ten years remaining melt is 4.16 to 4.48 million km2 - a narrowing range.

That 2017 feeling wanes and waxes- just when it look :-Xs like the melting has some legs it slows again and vice-versa. There is, on average, 6% (19 days) of further low and highly variable extent losses to go. Could the melting season last a bit longer than that - Yes.  On the other hand, could extent loss do a 2017 and sharply reduce? Yes.

A September minimum in the range of 4.00 to 4.50 million km2 seems very probable, with the result of least drama at 4th place. It also seems highly probable that the data will show that melt was below average, considerably so.
"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)