365 day average extent poll

[gerontocrat]

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.

[gerontocrat]

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 ??

[gerontocrat]

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.

[gerontocrat]

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.

[Tor Bejnar]

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!

[gerontocrat]

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.

[gerontocrat]

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

[Paddy]

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.

[gerontocrat]

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

[gerontocrat]

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

[gerontocrat]

NSIDC 5 day extent reached a record low minimum 365 day trailing average on the 6th March.

If daily extent change is at average this reduction will cease on 23rd March and the average will start to increase. i.e. the 2021 melting season must be as strong as it was in 2020 to maintain the reduction in the 365 day average.

click images to enlarge

[interstitial]

thanks gerontocrat for this thread. extent seams to change without logic but 365 day average moves  more consistently.

[gerontocrat]

JAXA Sea Ice Extent data

The 365 day trailing average @ 9.636 million km2 is now 48k below the previous record low in early 2017. As long as 2021 daily extent remains below that of 2020, the reduction continues. But in 2020 from now  daily extent loss was mostly well above average. If 2021 daily extent loss from now is at average then the 365 day trailing average will reach its minimum of the 23rd March and then start to rise.

I hope the attached images help to show this.

click images to enlarge

[gerontocrat]

from JAXA Extent data

The 365 day trailing average extent bottomed out on 19th March at 9.634 million km2, some 49k below the previous minimum in 2017. Unless daily extent loss is well above the 10 year average, the 365 day trailing average extent will quickly increase for some considerable time.

[gerontocrat]

JAXA Arctic Sea Ice Data

I attach table and graphs of the 365 day trailing average of Arctic sea ice extent.

The average finally bottomed out of the 19th March at 9.334 million km2, some 49K below then previous record low in 2017. What happens from now depends entirely on how this melting season goes compared with 2020.

2020 was a strong melting season. If 2021 is only average, the trailing average of extent will rise.

click images to enlarge

[interstitial]

How likely is a "strong melting season"? I have this perception that the difference between min and max is increasing, with weather variations, because the ice is thinning but that may not be true.

[Glen Koehler]

    Dear Gero - any chance you could do an equivalent 365 running average as of March 31 2021 for either JAXA or NSIDC Area?

[gerontocrat]

    Dear Gero - any chance you could do an equivalent 365 running average as of March 31 2021 for either JAXA or NSIDC Area?

Yep

NSIDC Area - (JAXA doesn't give area data)

[gerontocrat]

From JAXA Extent data

Currently the average at 9.64 million km2 is 43k below the April 2017 minumum, but 6k above the current record low of the 19th March

The 2021 melting season waxes and wanes - stronger than 2020 and then weaker.
This makes all the difference to the direction of travel and projections of the future 365 day trailing average.

3 days of extent gains have put the projection back into an upward trajectory.

Table & Graphs attached.

[gerontocrat]

From JAXA Extent data

Currently the average at 9.64 million km2 is 37k below the April 2017 minumum, but 12k above the current record low of the 19th March

The April 2021 melting season waxed and waned - someimes stronger than 2020 but mostly weaker. This makes all the difference to the direction of travel and projections of the future 365 day trailing average.

April slow melt has put the projection back into an upward trajectory. May melt could easily reverse this - or not.

Table & Graphs attached.