Arctic Sea Ice : Forum

Cryosphere => Arctic sea ice => Topic started by: Paddy on September 12, 2019, 11:37:24 AM

Title: 365 day average extent poll
Post by: Paddy on September 12, 2019, 11:37:24 AM
Based on Gerontocrat's 365 day Arctic sea ice trailing average extent graphs (https://forum.arctic-sea-ice.net/index.php/topic,2533.msg228175.html#msg228175). When would you next expect to see a new record low 365 day trailing average?

Currently the average is about 160k above the record in 2016 (eyeball estimate from said graph, so please take with a pinch of salt).

EDIT: As pointed out by Gerontocrat, please note that we're talking about JAXA extent here.
Title: Re: 365 day average extent poll
Post by: blumenkraft on September 12, 2019, 11:42:33 AM
Good poll!

I went with early 2020.
Title: Re: 365 day average extent poll
Post by: crandles on September 12, 2019, 12:33:47 PM
2019 below 2018 by 460k so if this gap maintained, average declines at a little over 1k per day. This isn't enough to do it in 2019. Also lines tend to be spread out most at minimum, group together much more in November and 2018 stayed rather low into early October.

So I have to conclude 2019 is looking rather unlikely.

Early 2020 seems plausible and is my guess but little chance of earlier and much more chance of being later, possibly quite a bit later.
Title: Re: 365 day average extent poll
Post by: Paddy on September 12, 2019, 01:40:49 PM
I went for "within the first 3 months of 2020", since we had a long period at or near record minimum between the end of March and August this year, which might well contribute to an overall average 365 day minimum if extent stays pretty low for the next 6 months or so; but from late October last year to March of this year the extent was relatively high, so we'd need much of that period to no longer be part of the trailing average to make a new record. 

Time will tell, though.
Title: Re: 365 day average extent poll
Post by: gerontocrat on September 12, 2019, 02:29:45 PM
Based on Gerontocrat's 365 day Arctic sea ice trailing average extent graphs (https://forum.arctic-sea-ice.net/index.php/topic,2533.msg228175.html#msg228175). When would you next expect to see a new record low 365 day trailing average?

Currently the average is about 160k above the record in 2016 (eyeball estimate from said graph, so please take with a pinch of salt).
Thanks, Paddy (maybe)

Need to emphasis it is JAXA** Extent.

Here is a table of the current position I was using for casual use by myself.

As noted above, it all depends on how quickly 2019 re-freezes compared with 2018.

_______________________________________________
**I have similar 365 day graphs for NSIDC Area & Extent - area especially tells a somewhat different story.

I will post them after today's NSIDC data has been swallowed by my machine.
Title: Re: 365 day average extent poll
Post by: gerontocrat on September 12, 2019, 04:25:23 PM
The NSIDC Extent and AREA graphs & tables attached.

NSIDC 365 day Extent follows JAXA Extent trends very closely, the NSIDC extent always a bit abve JXA extent.

NSIDC 365 day Area is much further behind the record minimum than extent, and the daily area difference with 218 is diminishing fast, slowing the daily drop in 365 day area.

This is likely to be replicated in the extent data, simply because usually the winter extents get much closer together.
Title: Re: 365 day average extent poll
Post by: Stephan on September 12, 2019, 08:34:09 PM
I do not see a 365-trailing average below the 2016 minimum in 2019. But it is likely to happen somewhen between Feb-Mar 2020, as already indicated by gerontocrat some weeks ago. Unless a very rapid and sustaining refreeze will occur Nov-Dec 2019 I see no other "right" bin than Jan-March 2020.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 15, 2019, 09:04:50 PM
Things have changed.

The difference in JAXA Extent 2019 from 2018 reduced from 545k on the 14 September to just 243k on 2nd October. This pushed the date of a straight line projection of a new 365 day average record low from early January 2020 to early May 2020.

But since that date the very low extent 2019 extent gains has increased the difference with 2018 to 597k by the 14th October. So the date of a new record low is back to early January.

There is 136 k to go to a new record 365 day low, (9,683,735 km2), with the daily change on 14th October at 1,589 k.

Outlook- from this date 2018 daily gain was fairly high to very high in the next month.
IFF (if & only if) 2019 extent gains are generally at or below average, we could see a record 365 day average low late in this year.

Data table & graphs attached
_________________________________________
ps: If what is happening with extent this month had happened last month - there would have been many headlines
Title: Re: 365 day average extent poll
Post by: Paddy on October 19, 2019, 07:13:57 PM
.
IF (if & only if) 2019 extent gains are generally at or below average, we could see a record 365 day average low late in this year.

That would be a pretty shocking outcome.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 21, 2019, 12:14:10 PM
A new record low 365 day average extent in 2019 (JAXA Extent data as at 20th October 2019)

On the 20th October 2018 extent is 510 k greater than 2019.

There is 127 k to go to a new record 365 day low, (9,683,735 km2), with the daily reduction in the 365 day average on 20th October at 1,400 k. So the date of a new record low is back to late January.

But if you look at the plume of daily gains from now to end November (attached), you will see that 2018 gains were far above average, indeed the highest in the last 10 years.

IFF (if & only if) 2019 extent gains are generally at average, this will increase the difference between 2018 and 2019 extent substantially, which would increase the daily reduction in the 365 day average substantially. Just maybe we could see a record 365 day average low very late in this year. However, there are only 72 days to 31st December.

Data table & graphs attached
_________________________________________
ps: If what is happening with extent this month had happened last month - there would have been many headlines
[/quote]
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 28, 2019, 12:47:11 PM
A new record low 365 day average extent in 2019 ?
(JAXA Extent data as at 27th October 2019)


On the 27th October 2018 extent is 556 k greater than 2019.

There is 116 k to go to a new record 365 day low, (9,683,735 km2), with the daily reduction in the 365 day average on 27th October at  just over 1,400 k. So the date of a new record low is currently circa mid January.

But if you look at the plume of daily gains from now to mid Decvember (attached), you will see that 2018 gains were far above average, indeed for much of the time the highest in the last 10 years. On the other hand, recent Arctic extent gains have been extremely high.

IFF (if & only if) 2019 extent gains are generally at average, this will increase the difference between 2018 and 2019 extent substantially, which would increase the daily reduction in the 365 day average substantially. Just maybe we could see a record 365 day average low very late in this year. However, there are only 65 days to 31st December.

On the other hand, if extent gains stay high and above those in 2018, one could see a new record low delayed or even put out of reach once 2019 extent is greater than 2018.

I still plump for an early 2020 record low - (Jan to April)

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 03, 2019, 01:41:12 PM
A new record low 365 day average extent in 2019 looking much less likely
First 3 months in 2020 seems a more likely time-frame.

JAXA Extent data as at 2nd November 2019


On the 2nd November 2018 extent is a (reduced) 418 k greater than 2019.

There is 110 k to go to a new record 365 day low, (9,683,735 km2), with the daily reduction in the 365 day average on 2 November at  just under 1,150 k. So the date of a new record low is currently early February.

But if you look at the plume of 2018 daily gains for the rest  December (attached), you will see that 2018 gains were above average. On the other hand, recent Arctic extent gains have been extremely high, though starting to moderate.

IFF (if & only if) 2019 extent gains are generally at average, this will increase the difference between 2018 and 2019 extent substantially, which would increase the daily reduction in the 365 day average substantially. Just maybe we could see a record 365 day average low very late in this year. However, there are only 59 days to 31st December.

On the other hand, if extent gains stay high and above those in 2018, one could see a new record low delayed or even put out of reach once 2019 extent is greater than 2018.

I still plump for an early 2020 record low - (Jan to March)

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 12, 2019, 07:15:45 AM
A new record low 365 day average extent in 2019 looking much less likely
First 3 months in 2020 seems a more likely time-frame.

JAXA Extent data as at 11 November 2019


On the 2nd November 2018 extent is a (slightly reduced) 393 k greater than 2019.

There is 100 k to go to a new record 365 day low, (9,683,735 km2), with the daily reduction in the 365 day average on 2 November at  just under 1,100 k. So the date of a new record low is currently early February.

But if you look at the plume of 2018 daily gains (attached) for the rest of November, you will see that 2018 gains were above average. In December, 2018 gains were below average.

There are only 50 days to 31st December. What will 2019 extent gains be?

I still plump for an early 2020 record low - (Jan to March)

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 17, 2019, 12:17:23 PM
A new record low 365 day average extent in 2019 looking very unlikely
First 3 months in 2020 seems a more likely time-frame.

JAXA Arctic Sea Ice Extent data as at 16 November 2019


On the 16th November 2018 extent is 443 k greater than 2019.

There is 95 k to go to a new record 365 day low, (9,683,735 km2), with the daily reduction in the 365 day average on 16 November at  just over 1,200 km2. So the date of a new record low is currently February 2020.

But if you look at the plume of 2018 daily gains (attached) for the rest of November, you will see that 2018 gains were above average. In December, 2018 gains were below average.

There are only 45 days to 31st December. What will 2019 extent gains be?

I still plump for an early 2020 record low - (Jan to March)

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: Phil. on November 17, 2019, 03:22:14 PM
There is 95 k to go to a new record 365 day low, (9,683,735 km2), with the daily reduction in the 365 day average on 16 November at  just over 1,200 k. So the date of a new record low is currently February 2020.

Should be 1,200 i.e. not k.
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 25, 2019, 12:15:23 PM
A new record low 365 day average extent in 2019 is highly unlikely to impossible
First 3 months in 2020 seems a more likely time-frame.

JAXA Arctic Sea Ice Extent data as at 24 November 2019


On the 24th November 2018 extent is 647 k greater than 2019.

There is 82 k to go to a new record 365 day low, (9,683,735 km2), with the daily reduction in the 365 day average on 16 November at  just over 1,750 km2. So the date of a new record low is currently January 2020.

But if you look at the plume of 2018 daily gains (attached) for the rest of the year, you will see that 2018 gains are mostly below average from now to the end of the year. So if 2019 extent gains are at average or above, the difference in extent between 2019 and 2018 could quickly reduce. Also, in general, variations in extent between years reduce as winter progresses. This will reduce the daily reduction in the 365 daily average and thus lengthen the time to reach a record low - or even prevent that record low from happening.

There are only 37 days to 31st December. What will 2019 extent gains be?

I still plump for an early 2020 record low - (Jan to March)

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: binntho on November 25, 2019, 01:02:36 PM
Gerontocrat, your graph starts in 1990 as far as I can see. Is there any reason for that? A longer period would be interesting.
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 28, 2019, 12:43:56 PM
Gerontocrat, your graph starts in 1990 as far as I can see. Is there any reason for that? A longer period would be interesting.
JAXA extent data in the earlier years was posted into their tables only on each 2nd day.There are also many gaps of several days. So average 365 day data is not a simple calculation. I am gradually filling in these gaps with interpolations but then there will always be a caveat in the results. It is also a pain in the arse getting several extra thousand lines of data into the averages sheet even though I use a nice little algorithm  to do it. Patiencia.

Meanwhile......
Here are the graphs & table again.

Title: Re: 365 day average extent poll
Post by: gerontocrat on December 01, 2019, 02:16:55 PM
A new record low 365 day average extent in 2019 is in the range of highly unlikely to impossible
First 3 months in 2020 or even later seems a more likely time-frame.


JAXA Arctic Sea Ice Extent data as at 30 November 2019

There is 72 k to go to a new record 365 day low, (9,683,735 km2), with the daily reduction in the 365 day average down to just under 1,400 km2. So the date of a new record low is currently late January 2020.

On the 30th November 2019 the extent difference with 2018 has reduced to 499 k less  than 2018. The effect is a continuous reduction in the daily loss in the 365 day average, which in turn made the date for a new record low 365-day-average later. (See table attached).

And if you look at the plume of 2018 daily gains (attached) for the rest of the year, you will see that 2018 gains are mostly below average from now to the end of the year. So if 2019 extent gains are at average or above, the difference in extent between 2019 and 2018 could quickly reduce. Also, in general, variations in extent between years reduce as winter progresses. This will reduce the daily reduction in the 365 daily average and thus lengthen the time to reach a record low - or even prevent that record low from happening.

I still plump for an early 2020 record low - (Jan to March), but have no scientific basis for that guess

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 09, 2019, 08:15:03 AM
5 days of extreme sea ice extent gains has put the cat amongst the pigeons.
A new record low 365 day average extent in 2019 is in the range of impossible to infinitely impossible

A week ago I wrote....
 
Quote
So if 2019 extent gains are at average or above, the difference in extent between 2019 and 2018 could quickly reduce. Also, in general, variations in extent between years reduce as winter progresses. This will reduce the daily reduction in the 365 daily average and thus lengthen the time to reach a record low - or even prevent that record low from happening.
And on the 7th December 2019 extent became greater than 2018 - so the date for a new record low is currently The 12th of Never and that's a long, long time.

So what will happen from now? Will 2019 extent stay above 2018 or will extent gains from now become below average?

In defiance of probability I still plump for an early 2020 record low - (Jan to March), but have no scientific basis whatsoever for that guess

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 15, 2019, 07:06:41 PM
As at 14 December 2019 reductions in the 365 day average have stalled.
A new record low 365 day average extent in 2019 is in the range of impossible to infinitely impossible

2 weeks ago I wrote....
 
Quote
So if 2019 extent gains are at average or above, the difference in extent between 2019 and 2018 could quickly reduce. Also, in general, variations in extent between years reduce as winter progresses. This will reduce the daily reduction in the 365 daily average and thus lengthen the time to reach a record low - or even prevent that record low from happening.
And on the 7th December 2019 extent became greater than 2018 - so the date for a new record low is currently The 12th of Never and that's a long, long time.

So what will happen from now? Will 2019 extent stay above 2018 or will extent gains from now become below average?

In defiance of probability I still plump for an early 2020 record low - (Jan to March), but have no scientific basis whatsoever for that guess

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 29, 2019, 10:21:25 AM
As at 28 December 2019 reductions in the 365 day average have stalled and reversed to increases. A new record low 365 day average extent in 2019 is in the range of impossible to infinitely impossible

2019 daily extent gains have been well above 2018 for most of December, so 2019 sea ice extent is well above 2018. The date for a new record low is currently "The 12th of Never and that's a long, long time".

So what will happen from now? In the New Year, if 2020 daily extent gains are at average, 2020 extent will fairly rapidly become lower than 2019 extent, and thus progress to a new record low 365 day trailing average. However, by late March 2019 started its rapid extent losses towards a 2nd lowest extent minimum.

Logic suggests that a new record low could happen by late March 2020, but after that would require very strong early melt even greater than that of 2019

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: gerontocrat on January 04, 2020, 12:03:09 PM
As at 3 January 2020

i]As reductions in the 365 day average stalled and reversed to increases a new record low 365 day average extent in 2019 did not happen[/i]

The date for a new record low is currently "The 12th of Never and that's a long, long time". However, recent low extent gains means that 2020 extent is now only 3 k above 2019.

So what will happen from now?  2020 daily extent gains have to be below average for the 365 day average to start falling again, and that is in the lap of the weather gods.

Data table & graphs attached
_________________________________________
Title: Re: 365 day average extent poll
Post by: Paddy on January 19, 2020, 07:40:49 AM
I'm going to call it - the majority of us, myself included, were probably wrong. I think there's too much ground to make up in the next two months with recent gains.
Title: Re: 365 day average extent poll
Post by: jdallen on January 23, 2020, 12:07:01 AM
I'm going to call it - the majority of us, myself included, were probably wrong. I think there's too much ground to make up in the next two months with recent gains.
Now the actual fun starts - dissecting why, and what additional factors we should be examining in making our predictions.
Title: Re: 365 day average extent poll
Post by: gerontocrat on January 27, 2020, 01:56:19 PM
As at 26 January 2020

Sea ice extent has continued its strong recovery and is well above last year.

2019 was second lowest extent at minimum. 2020 extent loss would have to be huuuge to get below 2019.

Therefore the probability must be that in 2020 the 365 day average will increase, not decrease.

The date for a new record low is currently "The 12th of Never and that's a long, long time". ________________________________________________________
Title: Re: 365 day average extent poll
Post by: philopek on January 28, 2020, 10:33:56 PM
As at 26 January 2020

2019 was second lowest extent at minimum. 2020 extent loss would have to be huuuge to get below 2019.


doesn't that depend on this year's sea-ice maximum as well or solely even ?

i mean who says that extend growth doesn't end prematurely this season ?

peripheries have been and still are very warm as compared to other years that will have an impact on ocean temps and snow cover as well as ice thickness and that again could well make this freezing season end surprisingly early, of course, as always, depending on the wether in a bout a months time. +/- 2 weeks.

just something to consider, i have no specific opinion about this because it has shown to be in vain to try to predict what will be the situation in 8 months from now.
Title: Re: 365 day average extent poll
Post by: Paddy on July 17, 2020, 06:55:16 AM
How is this metric looking at present, gerontocrat? Seems like the last six months will have been very up and down.
Title: Re: 365 day average extent poll
Post by: oren on July 17, 2020, 07:08:13 AM
I think that to get a new record low in 365-day extent will require a poor refreeze season (as we had in 2016/17). It will not be enough to have a low Sep minimum, as 2020 was rather high during winter, though I haven't run the numbers to back this up.
Title: Re: 365 day average extent poll
Post by: Paddy on July 17, 2020, 10:02:15 AM
I think that to get a new record low in 365-day extent will require a poor refreeze season (as we had in 2016/17). It will not be enough to have a low Sep minimum, as 2020 was rather high during winter, though I haven't run the numbers to back this up.

You're probably right.  Right now, for each day that extent stays 600k km2 lower than the same date in 2019, the 365 day average will be dropping by over 1600 km2, and 2020 has been somewhat below 2019 since late May.  However, the 365 day average would have been climbing slowly from January to May, when 2020 was either tied with 2019 or above it, so we won't be down to the mini-trough in annual average in December 2019 yet, never mind getting anywhere close to threatening the record.
Title: Re: 365 day average extent poll
Post by: oren on July 17, 2020, 10:12:58 AM
It occurs to me Gero did an update of this recently in the data thread.

JAXA Sea Ice Extent - 365 Day Averages

Around this time last year it looked as if 2019 extent would be low enough to make a new record low 365 day trailing average extent. But came late autumn and winter 2019-20 and extent rebounded.

So here we are again, 2020 extent so far below 2019 extent as to possibly make a new record 365 day low later this year. It's all about whether 2020 extent will stay below 2019 extent and by how much.

Extent on this day is already 113k below the 1980's average with about 60 days to minimum. The table attached shows extent must reduce by 564k before it is below the highest minimum in the current century.

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=2975.0;attach=275275;image)

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=2975.0;attach=275278;image)
Title: Re: 365 day average extent poll
Post by: gerontocrat on July 17, 2020, 11:55:11 AM
I think that to get a new record low in 365-day extent will require a poor refreeze season (as we had in 2016/17). It will not be enough to have a low Sep minimum, as 2020 was rather high during winter, though I haven't run the numbers to back this up.
Not running the numbers was a mistake...

IFF 2020 extent continues below 2019 by the same amount as on the 16th July, the new record low would occur on the 29th September 2020.

Also to remember is that 2019 refreeze, once it got going (late) was really fast and ended up with a maximum of 10th lowest in the satellite record.. As long as extent is below that of a year ago the 365 day average will continue to decline.

So I reckon there is a good chance of a new record low in 2020 and may even decline further through the 2020-2021 winter.
___________________________________________
Title: Re: 365 day average extent poll
Post by: Paddy on July 18, 2020, 04:53:24 PM
Quote from: gerontocrat
IFF 2020 extent continues below 2019 by the same amount as on the 16th July, the new record low would occur on the 29th September 2020.
[/quote

Great analysis and figures as always, even if this does seem like a pretty big IF.

I'd personally reckon a new 365-day low may be most likely in early 2021, now (when 2020 ice cover was high). But obviously there's a lot that can change between now and then.
Title: Re: 365 day average extent poll
Post by: gerontocrat on July 21, 2020, 12:02:50 PM
JAXA Arctic Sea Ice Extent - 365 day trailing Average
Data as 20 July


The current high daily extent losses maintain the possibility of a record 365-day low in September.
For a record low in 2020, the average daily reduction has to be 709 km2, i.e. 2020 extent needs to be on average at least 259 k below 2019 extent.

On this day, the 20th July, 2020 is 642k less than 2019. So there is currently considerable leeway for a record low this year. But........
Title: Re: 365 day average extent poll
Post by: Paddy on July 30, 2020, 01:55:15 PM
JAXA Arctic Sea Ice Extent - 365 day trailing Average
Data as 20 July


The current high daily extent losses maintain the possibility of a record 365-day low in September.
For a record low in 2020, the average daily reduction has to be 709 km2, i.e. 2020 extent needs to be on average at least 259 k below 2019 extent.

On this day, the 20th July, 2020 is 642k less than 2019. So there is currently considerable leeway for a record low this year. But........

With the gap between 2019 and 2020 having shrunk to just 245k, I suppose this looks a tad more touch and go now... although of course we're getting to the point in the year when 2019's own sea ice loss slowed down.  Everything's still to play for.
Title: Re: 365 day average extent poll
Post by: gerontocrat on August 01, 2020, 11:29:50 AM
One week's stall in daily extent losses has reduced the 365 day daily losses. At the current rate it would be Feb 2021.

I make no predictions, whereupon I make one. This year could end up a washout or havoc could be unleashed on the ice, or it could be just average from now on..
Title: Re: 365 day average extent poll
Post by: gerontocrat on September 02, 2020, 08:46:42 AM
Suddenly there is a chance of a new record minimum 365 day average this year, except for one thing.

Last year, 2019 stunned me in October. The refreeze was so slow in happening that the 2019 October Monthly average was 700k below the linear trend, and 50k bnelow 2012, i.e. the record low October monthly minimum.

Maybe 2020 will match or come close to that low refreeze. If not, no record low 365 day  minimum this year.

Title: Re: 365 day average extent poll
Post by: gerontocrat on September 10, 2020, 10:44:14 AM
In the last week the chance of a new record minimum 365 day average this year has increased, although October may still delay it again..

Last year the refreeze was so slow in happening that the 2019 October Monthly average was 700k below the linear trend, and 50k below 2012, i.e. the record low October monthly minimum.

If 2020 will match or come close to that slow refreeze, a new 365 daty average low is likely. If not, no record low 365 day minimum this year. (I attach the October monthly average graph, with the 2020 value assuming average extent gains.)
Title: Re: 365 day average extent poll
Post by: Paddy on September 11, 2020, 07:53:35 AM
Should we repeat the original poll, but with new bins, maybe? Although we'd probably be guessing mainly about the October refreeze question if we did... and also about whether we'll repeat the relatively high Jan to March extents seen these last two years.
Title: Re: 365 day average extent poll
Post by: interstitial on September 11, 2020, 07:23:42 PM
maybe a rotating pole about what the average will be in 3 months?
Title: Re: 365 day average extent poll
Post by: Paddy on September 12, 2020, 03:37:39 AM
Perhaps just a sweepstake in this thread on month and year? In which case, I pick January 2021.
Title: Re: 365 day average extent poll
Post by: Aluminium on September 12, 2020, 07:41:54 AM
We need a poll about poll. :)
Title: Re: 365 day average extent poll
Post by: gerontocrat on September 12, 2020, 08:50:53 PM
Here is a bit of JAXA & DMI info on the subject.

The Plume shows that if 2020 freezes at an average rate then it won't take long for 2020 extent to exceed 2019 extent, simply because freeze was delayed a month in 2019.

Indeed the October 2019 monthly average was a record low - lower than 2012 by 150k and 690k below the trend value. But towards the end of October 2019 played catch up and in November and December extent gain was at or above average.  (Monthly graph attached)

So if 2020 is still below 2019 extent at the end of October the bet is still on for a 2020 record low 365 day average.

What about prospects for the October to December freeze - I attach two Arctic Ocean SST anomaly images - Sep 20 2019 and Sep 11 2020.
Title: Re: 365 day average extent poll
Post by: gerontocrat on September 12, 2020, 09:03:28 PM
And here is the current situation.....

but the dog doesn't give a damn.
Title: Re: 365 day average extent poll
Post by: gerontocrat on September 18, 2020, 10:41:57 AM
The expected(?) slow refreeze became a fast refreeze. At this rate a new record low 365 day average heads over the horizon.
Title: Re: 365 day average extent poll
Post by: jens on September 21, 2020, 10:42:57 AM
Interesting. I think a new 365-day record will happen somewhere in winter, as long as 2020/21 avoids the strong refreeze 2019/20 had. I think last winter had a strong freezing from about November onwards, moving gradually well down the order to 10th position or thereabouts. So this is where the window of opportunity for a new record opens up.
Title: Re: 365 day average extent poll
Post by: gerontocrat on September 21, 2020, 11:41:49 AM
And a 22k extent loss followed by a zero extent change puts 2020 in the frame again.

For a record low 365 day average in 2020 2020 extent has to be on average 275k less than 2019. On this day it is 330k.

The key for a record low 365 is for 2020 to match the slow refreeze from now to late October in 2019. From late October the 2019 refreeze accelerated. See the daily change graph Sept to Dec attached - (daily change smoothed into the 7 day trailing average).

If 2020 matches 2019 in a rapid refreeze from late October (or earlier) all bets are off.
Title: Re: 365 day average extent poll
Post by: KenB on September 21, 2020, 05:00:59 PM
Slightly off-topic given the explicit 365 day period in the title of this thread, but I was wondering what period of time ending today *would* constitute a record.  Surely, for example, the ten-year period ending today has lower average extent than any other 10-year period for which we have data.  I'd bet that's true for five years, too, but it's less sure.  What about two years? 1.5?

Of course, it's entirely possible that 2020 extent will stay low enough to cross under 2012 in some weeks or months, at which point the answer collapses suddenly to one day.     
Title: Re: 365 day average extent poll
Post by: gerontocrat on September 21, 2020, 05:22:52 PM
Slightly off-topic given the explicit 365 day period in the title of this thread, but I was wondering what period of time ending today *would* constitute a record.  Surely, for example, the ten-year period ending today has lower average extent than any other 10-year period for which we have data.  I'd bet that's true for five years, too, but it's less sure.  What about two years? 1.5?

Of course, it's entirely possible that 2020 extent will stay low enough to cross under 2012 in some weeks or months, at which point the answer collapses suddenly to one day.   
Look again at the graphs. You will see that the record low 365 day average was reached around the 1st April 2017. 2012 confuses the issue. Yes, in 2012 a record low in August & September, but March 2016 to March 2017 were lower than 2012 for most months.

Last year I thought at one time a new record low would happen in late 2019, simply because of the October monthly average being a record low. But then refreeze kicked in strongly. All 2020 extent has to do is to continue to stay below the 2019 extent, and then maybe in early 2021 to stay below the early 2021 extent for a new record low.

To answer your question (sort of). At the moment it looks as of it will be nearly 4 years since the last record low for a new record low. Before that it was about 4 years from the record low in about April 2013 to the record low on 1 April 2017.

What happens next? Not a clue.

Title: Re: 365 day average extent poll
Post by: gerontocrat on September 26, 2020, 01:53:52 PM
The current rapid refreeze has reduced substantially the amount 2020 sea ice extent is below 2019.
As a result a new record low in 2020 looks less likely, especially as 2019 extent gains were well below average from now to mid-October.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 02, 2020, 01:02:49 PM
But now daily extent gains have trended well below average so a 2020 record low is in play again.

On the other hand 2019 extent gains are also about to slow substantially, which led to a record low October monthly average last year. But from late October 2019 extent gains accelerated.

Graphs & table attached.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 05, 2020, 01:07:54 PM
A 2020 record low 365 day minimum still in play.

A small milestone just passed. In late 2019 the progress towards a record low petered out on the 6th December at a 365 day average of 9.751 million km2. The 4/10/2020 365 day average is just  below 9.750 million km2.

Title: Re: 365 day average extent poll
Post by: Paddy on October 05, 2020, 09:10:11 PM
A 2020 record low 365 day minimum still in play.

A small milestone just passed. In late 2019 the progress towards a record low petered out on the 6th December at a 365 day average of 9.751 million km2. The 4/10/2020 365 day average is just  below 3.750 million km2.

I think you mean 9.750?
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 05, 2020, 11:00:04 PM
A 2020 record low 365 day minimum still in play.

A small milestone just passed. In late 2019 the progress towards a record low petered out on the 6th December at a 365 day average of 9.751 million km2. The 4/10/2020 365 day average is just  below 3.750 million km2.

I think you mean 9.750?
bummer
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 16, 2020, 11:44:53 AM
From the 4th to the 14th October 2020 daily extent gains were mostly above 2019 extent gains. The possibility of a 2020 record low 365 day average seemed to slip away.

On the 15th, a very low daily 2020 extent gain reversed the trend. But will it continue enough to bring a 2020 record low into play? It all depends on whether 2020 follows 2012 and 2019 in an October rebound in arctic sea ice extent, or follows 2016, which did not.
Title: Re: 365 day average extent poll
Post by: Paddy on October 18, 2020, 04:15:40 PM
With high temps forecast for the ten days ahead, I expect the gap with 2019 can only widen in the immediate future. A new minimum this year looks ever more likely.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 18, 2020, 06:49:09 PM
Getting to be very interesting again...

click an image to make it bigger
Title: Re: 365 day average extent poll
Post by: oren on October 18, 2020, 07:14:01 PM
Thanks for these updates Gero.
Looking at the long term chart it is quite obvious that Arctic sea ice has not been stable since 2012 (or 2007) as some people think.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 19, 2020, 10:32:11 AM
Back on track for a 365 day trailing average record low in December 2020.

but......
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 21, 2020, 10:39:13 AM
Confidence in a record low 365 day trailing average in 2020 increases day by day.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 23, 2020, 01:12:58 PM
The 365 day trailing average continues to reduce at an accelerating rate. Given that 2019 daily extent gains are about to rocket upwards, this continue for at least a few days more. A reminder - it is the amount by which 2020 extent is lower than 2019 that determines the rate by which this average reduces.

A record low 365 day average in November is now a possibility, though perhaps not a probability.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 27, 2020, 12:04:58 PM
The 365 day trailing average continues to reduce at an accelerating rate. Given that 2019 daily extent gains continue to be very high this could continue for at least a few days more.

However, from around the 5th November daily gains in 2019 moderated. If, on the other hand, 2020 extent gains sharply increase due to the catch-up expected due to the very late late re-freeze, 2020 extent could catch up with 2019 very quickly indeed.

A reminder - it is the amount by which 2020 extent is lower than 2019 that determines the rate by which this average reduces.

A record low 365 day average in mid November is now a tantalising possibility.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 28, 2020, 01:59:15 PM
NSIDC Area Data

Here is the data on when NSIDC Area might be at a record low - and we are currently talking about mid-2021. Between now and then much can happen - and probably will.

____________________________________
ps: In a week or so I should be able to do the same for PIOMAS volume data to 0ct-31 / Nov-1.
Yet another very different story.



Title: Re: 365 day average extent poll
Post by: Tor Bejnar on October 29, 2020, 02:52:05 PM
A sine wave might be a smarter fit for the data (and then someone will need to figure out what the decadal influence is ...).  That polynomial certainly shows why extrapolating can be dangerous!
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 29, 2020, 02:53:12 PM
The 365 day trailing average continues to reduce at an accelerating rate. However, 2020 daily gains are on the increase.

A reminder - it is the amount by which 2020 extent is lower than 2019 that determines the rate by which this average reduces.

A record low 365 day average in mid November is still a tantalising possibility.
Title: Re: 365 day average extent poll
Post by: gerontocrat on October 29, 2020, 03:21:12 PM
A sine wave might be a smarter fit for the data (and then someone will need to figure out what the decadal influence is ...).  That polynomial certainly shows why extrapolating can be dangerous!
I left the polynomial fit on the graph just to remind myself that the best fit according to R2 is not always the best fit.
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 01, 2020, 12:03:05 PM
JAXA Sea Ice Extent 365 day average

Despite the current very high sea ice extent gains, a record low 365 day average in November still looks very possible.
Title: Re: 365 day average extent poll
Post by: Positive retroaction on November 01, 2020, 09:01:59 PM
thank you for all this data Gerontocrat
Are there any 365-day volume survey charts (month by month certainly)? I don't seem to have seen any on the forum
thank you
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 03, 2020, 06:46:59 PM
thank you for all this data Gerontocrat
Are there any 365-day volume survey charts (month by month certainly)? I don't seem to have seen any on the forum
thank you
You will see something on 365 day averages on this thread when we have the October PIOMAS data.

Meanwhile

NSIDC Sea Ice Area 365 day Average

In contrast wth JAXA extent, the NSIDC sea ice area 365 day average is still more than 300k above the early 2017 record low.
It is reducing, and could be a record low by mid-2021 if 2020-21 area stays well below 2019-20 area.
Title: Re: 365 day average extent poll
Post by: Positive retroaction on November 04, 2020, 12:02:01 AM
thank you for all this data Gerontocrat
Are there any 365-day volume survey charts (month by month certainly)? I don't seem to have seen any on the forum
thank you
You will see something on 365 day averages on this thread when we have the October PIOMAS data.


Thank you, so I will look that
And thank's for this interesting data for the extent
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 04, 2020, 05:21:27 PM
And here we are... PIOMAS Volume 365 Day Trailing Average.

The current record low was reached in August 2017 at 12,675 km3.
2020 daily volume has been lower than 2019 only since September 16th, and is currently 13,590 km3, 1,023 km3 above that record low.

So a long way to go, at the current rate a new record low in late 2022. BUT there are bound to be bumps in the road on the way.

Title: Re: 365 day average extent poll
Post by: Positive retroaction on November 04, 2020, 11:50:06 PM
Thank you, very informative
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 05, 2020, 11:14:57 AM
JAXA Extent Data

If 2020 daily extent gains do not substantially reduce in the next few days 2020 sea ice extent will become greater than 2019. At that time the 365 day trailing average would start to increase.
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 07, 2020, 11:08:06 AM
JAXA Extent Data

If 2020 daily extent gains do not substantially reduce in the next few days 2020 sea ice extent will become greater than 2019. At that time the 365 day trailing average would start to increase.
Wherupon 2020 daily extent gains have greatly reduced.
With just 25k to go, if extent gains from now are resonably close to the 10 year average a record low 365b day trailing average this year is pretty much a certainty.
Title: Re: 365 day average extent poll
Post by: Paddy on November 07, 2020, 11:31:51 AM
I think the question may start to be not whether we'll get a new minimum in the next few months, but when and how deep. Given how high 2020 went in Jan to March, it could go a fair bit deeper still in the first few months of next year.
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 11, 2020, 12:36:55 PM
Once again increases in extent gains push the date for a record low 365 day trailing average back to mid-December.

With just 22k reduction for a record low, what a tease.
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 16, 2020, 11:15:27 AM
JAXA Srctic sea ice extent data

I attach latest table and graph - just 18k to go for a new record low 365 day trailing average
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 19, 2020, 10:38:12 AM
JAXA Arctic sea ice extent data

I attach latest table and graphs

- just over 15k to go for a new record low 365 day trailing average,
- the trailing average just went below 9.7 million #km2.

The last graph attached shows why 2020 extent was catching up with 2019 from late October to early November and why now the gap is increasing.
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 22, 2020, 11:50:38 AM
JAXA Arctic sea ice extent data

I attach latest table and graphs

-12k to go for a new record low 365 day trailing average.
- at the current rate of daily reduction in the first week of December.....but
Title: Re: 365 day average extent poll
Post by: oren on November 22, 2020, 12:12:47 PM
2019 underperforms for the next 10 days, so it will be tough.
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 25, 2020, 12:23:04 PM
2019 underperforms for the next 10 days, so it will be tough.

JAXA Arctic sea ice extent data

,,,,but happened, and is likely to continue happening - see Oren's post

I attach latest table and graphs.
- 2020 extent now only 147k less than 2019,
-10k to go for a new record low 365 day trailing average, which  at the current rate of daily reduction happens on the 20th of December.....but could easily be delayed indefinitely.
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 27, 2020, 10:59:57 AM
2019 underperforms for the next 10 days, so it will be tough.

JAXA Arctic sea ice extent data

,,,,but happened, and is likely to continue happening - see Oren's post

I attach latest table and graphs.
- 2020 extent now only 147k less than 2019,
-10k to go for a new record low 365 day trailing average, which  at the current rate of daily reduction happens on the 20th of December.....but could easily be delayed indefinitely.
What a tease - 2020 daily extent gains drop to below zero...
Title: Re: 365 day average extent poll
Post by: gerontocrat on November 30, 2020, 11:46:32 AM
A new record low nearly there?
Just 6.8k and perhaps 8 days or so to go.

many a slip twixt cup and lip
Title: Re: 365 day average extent poll
Post by: Paddy on December 05, 2020, 09:13:41 AM
Not long now, surely.
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 05, 2020, 06:23:27 PM
Not long now, surely.
The tease continues...

2 days high extent gains sent the date out to the 22nd December.
Followed by 2 days of low extent gains bringing the date back to 11th December.

But with just 4.3k to go and very high extent gains in 2019 over the next few days should finish the job pdq ( bit my prophecies have a bad habit of....)

And after that - NSIDC extent and area and PIOMAS volume?
And how low will this current reduction in Jaxa exent takes us? Doing something about that now. Wait small
Title: Re: 365 day average extent poll
Post by: crandles on December 05, 2020, 06:34:05 PM
Is the next poll how long it stays at record low levels?  ;D
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 05, 2020, 08:20:47 PM
Is the next poll how long it stays at record low levels?  ;D
I'm thinking perhaps about how low will it go by date of Jaxa Maximum 2021, or say 15 March 2021.
being time limited also gives a bit of extra intertest to the freezing to maximum.

Untested graph attached
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 06, 2020, 12:42:49 PM
3.5k to go, and at the current rate 4 days, for a record low 365 day average.
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 07, 2020, 12:19:59 PM
A high Arctic sea ice extent gain slows down the365 day reduction a bit. This pushes the date of the record low back a day to 11th December, with 4 days and 2,75k km2 to go.

In 2019, Dec 7 & Dec 8 saw very high extent gains. This might accelerate progress to the record low.
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 08, 2020, 12:04:11 PM
2k km2 and 3? days to go for the new record low 365 day trailing average.
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 09, 2020, 11:30:53 AM
1k km2 and 1? days to go for the new record low 365 day trailing average.
Title: Re: 365 day average extent poll
Post by: Paddy on December 10, 2020, 09:55:54 AM
It look's like today's the day the graph ventures into new unmarked space.
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 10, 2020, 10:23:40 AM
It look's like today's the day the graph ventures into new unmarked space.
Yep
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 10, 2020, 11:20:05 AM
And this is what happens if daily extent change for the year from now proceeded every day at the 10 year average - the 365 trailing daily average bottoms out on 5th July 2021 at  9,478,473 km2.
Title: Re: 365 day average extent poll
Post by: Tor Bejnar on December 10, 2020, 06:50:41 PM
I enjoy unforeseen consequences on other people's tables with automatic calculations.  Geron's lovely chart indicates 110 km2 needs to be added to reach the minimum  ???  It reminds me of cartoons I love that show how much distance Wile E. Coyote has to run past the edge of a cliff before he can begin to fall.  (One thing that amazes me about Wile E. Coyote is that he stops completely before falling straight down.  He must have some super power air brakes!)
:)
Title: Re: 365 day average extent poll
Post by: Paddy on December 15, 2020, 06:16:48 AM
So this measure may be a bit niche for anyone to be issuing a press release... But does it seem likely at year's end that someone will publicise 2020 having the lowest annual average extent on record of, as seems likely, it's still number one on December 31st?
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 15, 2020, 12:57:09 PM
So this measure may be a bit niche for anyone to be issuing a press release... But does it seem likely at year's end that someone will publicise 2020 having the lowest annual average extent on record of, as seems likely, it's still number one on December 31st?
The odds are that it will still be lowest at Dec 31. It means that 2020 is the year with the lowest sea ice extent. In my mind it is more significant than (say) the record low Sept minimum of 2012 because we are talking about sustained periods of record low sea ice and record high open water.

But the annual minima is the one that get the headlines.
Title: Re: 365 day average extent poll
Post by: Paddy on December 15, 2020, 08:28:39 PM
So this measure may be a bit niche for anyone to be issuing a press release... But does it seem likely at year's end that someone will publicise 2020 having the lowest annual average extent on record of, as seems likely, it's still number one on December 31st?
The odds are that it will still be lowest at Dec 31. It means that 2020 is the year with the lowest sea ice extent. In my mind it is more significant than (say) the record low Sept minimum of 2012 because we are talking about sustained periods of record low sea ice and record high open water.

But the annual minima is the one that get the headlines.

I agree it's important, but I just don't know if anyone is measuring it off these forums. I was thinking that they may well measure the annual average at the end of the year, though, although as you say, this would yield fewer headlines than the annual minimum.

EDIT: BTW, as another question, are we also seeing a new 365 day minimum for NSIDC extent and area?
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 19, 2020, 10:50:53 AM
So this measure may be a bit niche for anyone to be issuing a press release... But does it seem likely at year's end that someone will publicise 2020 having the lowest annual average extent on record of, as seems likely, it's still number one on December 31st?
The odds are that it will still be lowest at Dec 31. It means that 2020 is the year with the lowest sea ice extent. In my mind it is more significant than (say) the record low Sept minimum of 2012 because we are talking about sustained periods of record low sea ice and record high open water.

But the annual minima is the one that get the headlines.
6 days of above average extent gains and lo and behold, extent that was 2nd lowest becomes 5th lowest in the satellite record which incudes 2020 extent being higher than 2019 extent.

The  365 day average therefore increases..
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 21, 2020, 11:55:50 AM
JAXA 365 day average extent continues to go in reverse, and will continue to do so until extent increases reduce significantly below those in 2019.
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 24, 2020, 11:34:40 AM
JAXA Extent

Slow down in Arctic sea ice extent daily increases halts 385 day average reversal to gains.
What will the future bring?

Some data to confuse you more attached.
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 28, 2020, 12:40:22 PM
JAXA Extent data
Below average Arctic sea ice extent gains sends 365 day trailing average into reduction mode again.

However, further reductions require extent gains in 2020-21 to be below 2019-20 extent gains. This is very possible until March, but after that ??
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 29, 2020, 03:57:25 PM
NSIDC Area 365 Day Trailing Average

If 2020/21 daily Area stays below 2019/20 daily area then a new record low NSIDC Area 365 Day Trailing Average would happen sometime in mid 2021.

But the plume (3rd attachment) shows that from March 20 the melting season went off at a gallop.
If the 2921 melting season does not at least equal that then a new record low is indefinitely postponed.
Title: Re: 365 day average extent poll
Post by: gerontocrat on December 29, 2020, 04:07:26 PM
NSIDC EXTENT 365 Day Trailing Average

If 2020/21 daily extent stays below 2019/20 daily extent then a new record low NSIDC Extent 365 Day Trailing Average would happen sometime in mid 2021.

But the plume (3rd attachment) shows that from March 20 the melting season went off at a gallop.
If the 2021 melting season does not at least equal that then a new record low is indefinitely postponed.
Title: Re: 365 day average extent poll
Post by: Tor Bejnar on December 30, 2020, 12:11:10 AM
Quote
If the 2921 melting season does not at least equal that then a new record low is indefinitely postponed.
Maybe not "indefinite", but 900 years is a long time!
Title: Re: 365 day average extent poll
Post by: gerontocrat on January 21, 2021, 12:55:47 PM
I attch a table and graphs of the 365 day trailing average.

The average continues to decline - hesitantly as daily 2021 extent is below and sometimes above the 2020 daily extent.

The projection shows a decline to mid March and then the 365 day trailing averge increases. This is because the projection assumes the 2021 melting season daily extent losses will be average, while 2020 saw a very strong melting season. See the last image.

Who knows what the reality of the 2021 melting season will be? Not me.
Title: Re: 365 day average extent poll
Post by: gerontocrat on February 01, 2021, 01:33:56 PM
Once again I attach a table and graph of the 365 day trailing average.

The average continues to decline - hesitantly as daily 2021 in January extent was sometimes below and sometimes above the 2020 daily extent. The 365 day trailing average is now just over 20k less than the previous minimum of August 2017.

The projection shows a decline to mid March and then the 365 day trailing average increases. This is because the projection assumes the 2021 melting season daily extent losses will be average, while 2020 saw a very strong melting season, starting immediately after the maximum in mid-March. See the plume graph.

Who knows what the reality of the 2021 melting season will be? Not me.

Click image to enlarge
Title: Re: 365 day average extent poll
Post by: Paddy on February 08, 2021, 01:03:29 PM
I've been off the forum for a while, but thank you for answering my queries about the NSIDC data and for keeping us all updated on the JAXA situation.
Title: Re: 365 day average extent poll
Post by: gerontocrat on February 15, 2021, 03:44:06 PM
Once again I attach a table and graph of the 365 day trailing average (JAXA extent data)

The average continues to decline - hesitantly as daily extent was sometimes below and sometimes above the 2020 daily extent. At 9.656 million km2 the 365 day trailing average is now just over 27k less than the previous minimum of August 2017.

If daily extent change from now is at the 10 average, the 365 day average will decline erratically to a low of 9.647 million on the 19th March and then increase strongly, simply because 2020 saw a very strong melting season, starting immediately after the maximum in mid-March. See the plume graph.

For the 365 day trailing average to decline further requires the 2021 melting season to do a Usain Bolt from the starting blocks and tend to above average melting for the melting sason. But who knows what the reality of the 2021 melting season will be? Not me.

Click image to enlarge
Title: Re: 365 day average extent poll
Post by: gerontocrat on March 01, 2021, 09:14:07 AM
Once again I attach a table and graph of the 365 day trailing average (JAXA extent data)

The average continues to decline. At 9.644 million km2 the 365 day trailing average is now 39k less than the previous minimum of August 2017.

If daily extent change from now is at the 10 average, the 365 day average will decline erratically to a low of 9.626 million on the 23rd March and then increase strongly, simply because 2020 saw a very strong melting season, starting after the maximum in mid-March. See the plume graph.

For the 365 day trailing average to decline further requires the 2021 melting season to do a Usain Bolt from the starting blocks and tend to above average melting for the melting sason. But who knows what the reality of the 2021 melting season will be? Not me.

Click image to enlarge