2018 sea ice area and extent data

[El Cid]

Looked for an extent-vs-time graph where the extent is the average over the preceding year and found it here (nice site!): https://sites.google.com/site/marclimategraphs/_/rsrc/1536226652563/collection/G12.jpg

Interesting & looks reasonably linear.

Just eye-balling, I don't see a lot of year-to-year auto-correlation so perhaps there is just the long term trend and the ice extent does, to a good approximation, forget what happened last year.

Here is something on similar lines using NSIDC Daily Extent previous 365 days average. Going down.

These  charts seem to be quite convincing. I wondered about "the stall" before, but I now believe that the downtrend is alive and intact, although a bit slower than before - probably because the central pack is a hard nut to crack.

[gerontocrat]

NSIDC Total Area as at 1 October (5 day trailing average) =  3,511,401 km2

Total Area gain 40 k. Below average area gain continues, so area now 279 k less than 2017.
 
Peripheral Seas gain       16 k, of which 12k in the Greenland Sea
Central Seas     gain       20 k,                                 
Other Seas       gain        4 k, mostly Okhotsk - mask change ?

Individual Seas
Beaufort Sea                 gain      6 k
Canadian Archipelago    gain     11 k
East Siberian Sea (ESS) gain      1 k ,
Central Arctic Sea          gain      1 k Losses at an end?

Freezing has taken hold but may very well continue to be slow. Attention switches to the pace of that freezing and where it is happening.

It has been very cold, is very cold, and will continue to be very cold in the Canadian Archipelago and Northern Canada.

Note - Is this not the day of the month NSIDC fiddles with the mask so data might be wobbly?

[Eco-Author]

Seems natural that if ridges form over Beaufort a trough will form just behind it over CAA Hudson, which also plays into lows naturally forming over Hudson most of the time...

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

October 2^nd, 2018: 4,734,635 km², an insignificant increase of 321 km²
2018 is the 3^rd lowest on record.

[Stephan]

Step by step 2018 SIE comes closer to the value of 2007...

[gerontocrat]

JAXA ARCTIC EXTENT 4,734,635 km2（October 2, 2018）

Just to add to Juan's post  -

- Extent increase a tiny 321 km2,
- Extent is 355 k  (7.5 %) below the 2010's average extent on this date,
- Extent is 406 k (8.6 %) below 2017 on this date.
- freezing to date from minimum is 477k (63%) less than the 10 year average
- on average 7.6% of the increase in extent done.

An extra line in the table based on average extent increase in the last 5 years has been added. This is because extent gain in 2012-13 was so large (rebound from record low minimum) that it distorts the average.

GFS says the Arctic temperature anomaly will rise from 2.7 to over +4 degrees celsius by Saturday (and beyond) and that warmth coming from the Russian side will reach to the north of the CAA and the north coast of Greenland.. i.e. outlook is for slow extent increase for the next 5 days and perhaps for the next 10 days. We are observing an event unfolding which perhaps would have caused a real kerfuffle it it had happened during the melting season.

ps: The opposite is happening in the Antarctic - melting has barely started, if at all.

[Darvince]

That is an impressively small change - what was the last time the day-to-day extent changed by less than 1,000 sqkm? Or less than today's?

[gerontocrat]

That is an impressively small change - what was the last time the day-to-day extent changed by less than 1,000 sqkm? Or less than today's?

Yesterday.
But seriousy, extent has decreased on 9 days in October since 2002. In 2016 for 2 days in a row. On my phone so can't tell you the exact days.

[Darvince]

Thanks for that, I'd also like to know the last date that was between 1,000 square kilometers gained and 1,000 square kilometers lost.

[Phil42]

Thanks for that, I'd also like to know the last date that was between 1,000 square kilometers gained and 1,000 square kilometers lost.

Intersting question, here is what I found:

• It usually happens around 3-5 times a year (mostly but not exclusively around maximum or minimum).
• The last time it happened was the 23. September 2017, a drop of 458km².
• The smallest daily change I found was a drop of 12km² dated 15. September 1989.
• It has never happened for more than 2 consecutive days.

[gerontocrat]

NSIDC Total Area as at 2 October (5 day trailing average) =  3,552,841 km2

Total Area gain 41 k. Slightly below average area gain continues, so area now 289 k less than 2017.

Peripheral Seas gain       13 k, of which 10k in the Greenland Sea
Central Seas     gain       24 k,                                 
Other Seas       gain        4 k, mostly Okhotsk - on sheltered coastal fringes

Individual Seas
Beaufort Sea                 gain    14 k
Canadian Archipelago    gain      8 k
East Siberian Sea (ESS) LOSS    8 k ,
Central Arctic Sea          gain      9 k Losses at an end?

Arctic temperature anomaly rising to +4.3 celsius by Saturday. But as darkness descends temperatures drop like a stone. The temperature map shows that despite the high anomaly, most of the Arctic is entering ice formation mode. Freezing has thus taken hold but may very well continue to be slow. Attention switches to the pace of that freezing and where it is happening.

It has been very cold, is very cold, and will continue to be very cold in the Canadian Archipelago and Northern Canada.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

October 3^rd, 2018: 4,763,771 km², an increase of 29,136 km²
2018 is the 3^rd lowest on record.

[gerontocrat]

JAXA ARCTIC EXTENT 4,763,771 km2（October 3, 2018）

Just to add to Juan's post  -

- Extent increase a less than average 29k km2,
- Extent is 376 k  (7.9 %) below the 2010's average extent on this date,
- Extent is 424 k (8.9 %) below 2017 on this date.
- freezing to date from minimum is 497k (61.8%) less than the 10 year average extent gain,
- on average 8.1% of the increase in extent done.

An extra line in the table based on average extent increase in the last 5 years has been added. This is because extent gain in 2012-13 was so large (rebound from record low minimum) that it distorts the average.

GFS says the Arctic temperature anomaly will rise from 2.7 to over +4 degrees celsius by Saturday (and beyond) and that warmth coming from the Russian side will reach to the north of the CAA and the north coast of Greenland. i.e. outlook is for slow extent increase for the next 5 days and perhaps for the next 10 days. We are observing an event unfolding which perhaps would have caused a real kerfuffle it it had happened during the melting season.

ps: The opposite is happening in the Antarctic - melting has barely started.

[Ned W]

Here's a graph of JAXA extent around each year's minimum, starting four weeks before the minimum, and subtracting the minimum extent.  (i.e., the X values are shifted so that the day of each year's minimum is Day 29, and the Y values are shifted so that each year's minimum extent is 0).

I had been thinking that the refreeze was off to a very slow start, and it's true that the past week has been abnormally slow -- but overall, 2018 is in the middle of the pack for refreeze.  What's more unusual is the very late minimum, and the looooooonnnngggg ssssslllllooooowwww approach to the minimum during late August/September.

Relatedly, I keep track of how many days each year spends within 500k km2 of its minimum.  (In other words, this is a metric of how flat or steep the curve is around each year's minimum.)  During the JAXA record (2002-present), the fewest days below this threshold was 25 (in 2010 and 2016) and the most days was 46 (in 2006).  2018 is currently at 42 days, tied for second place with 2003 ... but 2018 is still well below the threshold, so it could easily set a new record.

[binntho]

That's a very interesting graph Ned W, thanks!

I had been thinking that the refreeze was off to a very slow start, and it's true that the past week has been abnormally slow -- but overall, 2018 is in the middle of the pack for refreeze.

But isn't it also true that generally, the lower the minimum, the faster the refreeze? That's certainly the feeling one gets. So 2018 would be unusual in that sense, i.e., low minimum (2010s average) AND slow refreeze.

[oren]

I think the lower the minimum the faster the refreeze, but also the later the minimum the faster the refreeze.

[Ned W]

That's a very interesting graph Ned W, thanks!

Thank you!

But isn't it also true that generally, the lower the minimum, the faster the refreeze? That's certainly the feeling one gets. So 2018 would be unusual in that sense, i.e., low minimum (2010s average) AND slow refreeze.

I used to think so, but apparently not.  At least there isn't anything approaching a statistically significant relationship, during the 2002-2018 JAXA record:

X-axis is the minimum, Y-axis is the refreeze during the first 12 days after the minimum.  The red dot is 2018.  Not much of an obvious trend there.

The freakishly-low dot at bottom is 2008, which apparently had an extremely slow start to the freezing season.

One could re-do this with volume rather than extent.  Would it make a difference?  I would bet "no" but YMMV.

[Ned W]

the later the minimum the faster the refreeze.

That one does seem to be true.  The data are noisy:

but the relationship is statistically significant (p-value = 0.025).

[Ned W]

There also doesn't seem to be any useful interaction between the magnitude of the minimum (low vs high) and timing of the minimum (late vs early) as a predictor of refreeze.  Basically, the magnitude of extent at minimum is useless for predicting refreeze.  The timing is somewhat useful.  The combination of the two does no better than just using timing alone.

[Stephan]

Ned W,
thank you for the re-analysis of data around the yearly minimum. It is an interesting plot and shows that the last two weeks are not so unusual as they appear to be.

[Stephan]

It is time to compare the Arctic SIE of September (average value) with the long-term trend from 1979 to today. Therefore I calculated the difference of each monthly average value from the 1979-2018 average value for each month and plotted this difference vs. time. See attached graph.

The September 2018 value lies slightly below the long-term linear trend of these differences.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

October 4^th, 2018: 4,804,196 km², an increase of 40,425 km²
2018 is the 3^rd lowest on record.

[gregcharles]

So, here's an interesting tidbit: the current lowest NIPR extent records for October 16 to 19 belong to 2007, the only remaining year before 2010 to have any of its days be the lowest extent. 2018 has a decent chance of ending that though.

[Feeltheburn]

Thanks for that, I'd also like to know the last date that was between 1,000 square kilometers gained and 1,000 square kilometers lost.

I wouldn't worry about day to day changes, which can be statistical noise, but rather week to week. Counting pixels to arrive at what part of the arctic has >15% ice and <85% water is not all that exact. It may also depend on the location of area blocks containing what pixels.

That said, the refreeze this year is unusually slow. How that will affect ultimate ice extent is unclear.

[gerontocrat]

JAXA ARCTIC EXTENT 4,804,196 km2（October 4, 2018）

Just to add to Juan's post  -

- Extent increase a less than average 40k km2,
- Extent is 402 k  (8.4 %) below the 2010's average extent on this date,
- Extent is 475 k (9.9 %) below 2017 on this date.
- freezing to date from minimum is 517k (59.8%) less than the 10 year average extent gain,
- on average 8.6% of the increase in extent done.

An extra line in the table based on average extent increase in the last 5 years has been added. This is because extent gain in 2012-13 was so large (rebound from record low minimum) that it distorts the average. The outcome from using the 10 year average extent gain from now is a maximum of 13.82 million km2, while from using the previous 5 years's average extent gain is 13.43 million km2, some 450,000 km2 less than the 2017 record low maximum of 13.88 million km2. 

GFS says the Arctic temperature anomaly will rise from 2.9 to over +4 degrees celsius by Saturday (and beyond) and that warmth coming from the Russian side has reached the north of the CAA and the north coast of Greenland. i.e. outlook is for slow extent increase for the next 5 days and perhaps for the next 10 days.

Perhaps when this relatively warm period ends, extent gain will rebound very strongly. But maybe the delay in freezing will also reduce thickening of the ice.

ps: The opposite was happening in the Antarctic - melting was barely started, but now seems to be underway.
[/quote]

[uniquorn]

Ned W,
thank you for the re-analysis of data around the yearly minimum. It is an interesting plot and shows that the last two weeks are not so unusual as they appear to be.

The unusual thing is the CAB extent. Offset by CAA and Greenland Sea.

[gerontocrat]

NSIDC Total Area as at 4 October (5 day trailing average) =  3 3,634,721 km2

Total Area gain 41 k. Slightly below average area gain continues, area now 300 k less than 2017.

Peripheral Seas gain       13 k, of which 8.5k in the Greenland Sea
Central Seas     gain       22 k,                                 
Other Seas       gain        6 k, 3k Okhotsk - 3k Hudson
CAB Seas
Beaufort Sea                 gain    19 k
Canadian Archipelago    gain      9 k
East Siberian Sea (ESS) LOSS    9 k ,
Central Arctic Sea          gain      4 k Losses at an end?

Arctic temperature anomaly rising to >4 celsius by Saturday. But as darkness descends temperatures drop like a stone. The temperature map shows that despite the high anomaly, most of the Arctic is entering ice formation mode. Freezing has thus taken hold but may very well continue to be slow. Attention switches to the pace of that freezing and where it is happening.

It has been very cold, is very cold, and will continue to be very cold in the Canadian Archipelago and Northern Canada.

Daily Extent down by 13k on 3 October but then up by 134k on the 4th.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

October 5^th, 2018: 4,849,613 km², an increase of 45,417 km²
2018 is the 3^rd lowest on record.

[gerontocrat]

JAXA ARCTIC EXTENT 4,849,613 km2（October 5, 2018）

Just to add to Juan's post  -

- Extent increase a less than average 45k km2,
- Extent is 428 k  (8.8 %) below the 2010's average extent on this date,
- Extent is 462 k (9.5 %) below 2017 on this date.
- freezing to date from minimum is 546k (58.2%) less than the 10 year average extent gain,
- on average 9.4% of the increase in extent done.

An extra line in the table based on average extent increase in the last 5 years has been added. This is because extent gain in 2012-13 was so large (rebound from record low minimum) that it distorts the average. The outcome from using the 10 year average extent gain from now is a maximum of 13.79 million km2, while from using the previous 5 years's average extent gain is 13.40 million km2, some 480,000 km2 less than the 2017 record low maximum of 13.88 million km2. 

GFS says the Arctic temperature anomaly will rise to  +4 degrees celsius by today (and beyond) and that warmth coming from the Russian side has reached the north of the CAA and the north coast of Greenland. i.e. outlook is for slow extent increase for the next 5 days and perhaps for the next 10 days.

Perhaps when this relatively warm period ends, extent gain will rebound very strongly. But maybe the delay in freezing will also reduce thickening of the ice.

ps: The opposite was happening in the Antarctic - melting was barely started, but now seems to be slowly underway.
[/quote]
[/quote]

[gerontocrat]

NSIDC Total Area as at 5 October (5 day trailing average) =  3,659,134 km2

Total Area gain 24 k. Well below average area gain, area now 325 k less than 2017.

Peripheral Seas gain       14 k, of which 8.5k in the Greenland Sea
Central Seas     gain        6 k,                                 
Other Seas       gain        4 k, 3k Okhotsk, 1k Hudson
CAB Seas
Beaufort Sea                 gain    15 k
Canadian Archipelago    gain      6 k
East Siberian Sea (ESS) loss      9 k ,
Central Arctic Sea          loss      6 k.

Arctic temperature anomaly rising to >4 celsius by Saturday or Sunday and beyond. But as darkness descends temperatures drop like a stone. Despite the high anomaly, most of the Arctic is entering ice formation mode. Freezing has thus taken hold but may very well continue to be slow. Attention switches to the pace of that freezing and where it is happening.

It has been very cold, is very cold, and will continue to be very cold in the Canadian Archipelago and Northern Canada.

Daily Extent down by 13k on 3 October but then up by 134k on the 4th and down by 26k on the 5th.

[gerontocrat]

Each of the 14 seas is telling a different story. For example, here are the area graphs for the four central seas that conventional wisdom tells us will be last to give up their ice.

[gerontocrat]

And here is the same data presented in a different way.

The graphs show the open water as a percentage of the total area of the sea for various periods of the year. Simply put, the area above the lines on the graph is ice, below is open water.

The first graph is just for the Canadian Archipelago (CAA). This is because I put this into a group consisting of the Hudson, the CAA and the Baffin as sort of climatically similar.

The second graph is a group consisting of the Eastern Siberia Sea (ESS), the Beaufort and the Central Arctic Sea. Open water is for most of the year still a small fraction of total area.

Atlantification and Pacification seem to be squeezing the ESS from both sides so may be heading towards becoming seasonal ice sea - but not yet?

[Stephan]

In the last four days ESS has lost about a quarter of its ice. I wonder whether it will reduce further on to a new yearly minimum ?!?

[gerontocrat]

On 5th October, the ESS at 115k area is third lowest in the satellite record. On that day area in 2012 area was just 71k and in 2007 was a mere 1.5 k. In contrast area on 5 October in 2013 was 629k. Volatility or what.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

October 6^th, 2018: 4,874,753 km², an increase of 25,140 km²
2018 is the 3^rd lowest on record.

[gerontocrat]

JAXA ARCTIC EXTENT 4,874,753 km2（October 6, 2018）

Just to add to Juan's post  -

- Extent increase a less than average 25k km2,
- Extent is 490 k  (10.1 %) below the 2010's average extent on this date,
- Extent is 560 k (11.5 %) below 2017 on this date.
- freezing to date from minimum is 610k (59.4%) less than the 10 year average extent gain,
- on average 10.3% of the increase in extent done.

An extra line in the table based on average extent increase in the last 5 years has been added. This is because extent gain in 2012-13 was so large (rebound from record low minimum) that it distorts the average. The outcome from using the 10 year average extent gain from now is a maximum of 13.72 million km2, while from using the previous 5 years's average extent gain is 13.33 million km2, some 550,000 km2 less than the 2017 record low maximum of 13.88 million km2. 

GFS says the Arctic temperature anomaly will rise to 4 degrees celsius by today (and beyond)  i.e. outlook is for slow extent increase for the next 5 days and perhaps for the next 10 days.

Perhaps when this relatively warm period ends, extent gain will rebound very strongly. But maybe the delay in freezing will also reduce thickening of the ice.

ps: The opposite is happening in the Antarctic - melting has barely started, very slowly underway.

[gerontocrat]

This morning, after a long illness, my computer died.
The autopsy tomorrow may determine whether resurrection is possible or what can be rescued from the corpse.

At least the files are in the cloud, but no machine means no updates and no more posts until........?

Sorry all.

[FishOutofWater]

Thanks for all the fish GC. Your contributions have been widely appreciated here. I hope you are able to get a new computer and get back running very soon.

[Shared Humanity]

This morning, after a long illness, my computer died.
The autopsy tomorrow may determine whether resurrection is possible or what can be rescued from the corpse.

At least the files are in the cloud, but no machine means no updates and no more posts until........?

Sorry all.

Your posts will be missed.

[oren]

Hopefully the revival will be swift!

[magnamentis]

This morning, after a long illness, my computer died.
The autopsy tomorrow may determine whether resurrection is possible or what can be rescued from the corpse.

At least the files are in the cloud, but no machine means no updates and no more posts until........?

Sorry all.

sure you soon shall have a new or repared machinery

shouldn't take much longer than a day to set up a new computer nowadays, good that you have backups though, i'm paranoid with backups, have 8 full backups spread around the globe LOL

see you soon then

[RealityCheck]

To quote a certain well-known comedy sketch: 'It's not dead, it's sleeping!'
(The Dead Parrot sketch, Monty Python. Classic)
Top tip for computers: I always replace mine after 10 years, whether I need to or not

[litesong]

I always replace mine after 10 years,......

Oh..... I'm 5+ years late.

[Juan C. García]

[ADS-NIPR-JAXA] ASI Extent.

October 7^th, 2018: 4,916,132 km², an increase of 41,379 km²
2018 is the 3^rd lowest on record.

[Stephan]

The distance to 2007 is reducing fast now...

[psymmo7]

This morning, after a long illness, my computer died.
The autopsy tomorrow may determine whether resurrection is possible or what can be rescued from the corpse.

At least the files are in the cloud, but no machine means no updates and no more posts until........?

Sorry all.

This is really sad.

It's ridiculous that in this day and age that a hardware deficiency should upset the continuity of this thread.

I would argue that GC (Gerontocrat - I hope its That's OK with you as an abbreviation) is performing a public service with his analyses and thoughtful comments so why don't we as a community crowdfund a replacement for him.

I would be prepared to organise a GoFundMe crowdfunding for say 3000 USD to allow GC to get some decent hardware.

If crowdfunders can raise 5000 USD for a new sofa for Elon Musk https://www.telegraph.co.uk/technology/2018/04/18/hundreds-internet-users-crowdfund-elon-musk-5000-new-sofa/ then I think this is the least the Arctic Sea Forum participants can do to show their appreciation of GC.

What do you think GC?

What do the other participants think?

Neven - Sorry to be off-topic  but I think the continuity of this "Area and Extent" thread is important - Please start a new thread if you think its appropriate.

[gerontocrat]

A kind thought, psymmo7, but please do not. It goes to the Doctor today for the autopsy. Something will turn up.

[Alexander555]

To get some decent hardware 

[Pmt111500]

Ah, sorry to hear about that <gerontocrat>. I guess the stall season starts to be over in the north polar region soonish. Will the Antarctic melt start in earnest to counter the inevitable winter Arctic growth of ice of 2018 to 2019? Will someone keep the global graphs running? Will ice on the Antarctic Seas melt at all this austral summer? (Insert conspiracy theory)

[litesong]

Hopefully the revival will be swift!

Even the Hubble Telescope gyros are mal-functioning.