Arctic Sea Ice Extent, Area, and Volume

[Typhoon Tip]

52 minutes ago, forkyfork said:

despite the good pattern ice is still below 2009, 2013, and 2014 on extent

It's like sitting at 4pm on the beach in Tahiti with an umbrella drink, Four hours is a long time though, you bargain internally ...while looms the flight back to mid March back door miasma Boston mere hours away.

[LibertyBell]

6 hours ago, Typhoon Tip said:

It's like sitting at 4pm on the beach in Tahiti with an umbrella drink, Four hours is a long time though, you bargain internally ...while looms the flight back to mid March back door miasma Boston mere hours away.

Hey John what's your sci fi book about? Does it have potential as a series?  Anything about long distance interstellar travel in it?

 

[ORH_wxman]

On 9/9/2021 at 10:27 AM, ORH_wxman said:

Area increased 45k to put us about 120k above the 9/1 min. Still too close to call the min, but another 100k or so increase over the next 3 days would probably do it.

We’ve increased another 70k or so since this and now we’re about 190k above the 9/1 minimum. We’re gonna need to see a big drop in the next couple days or I think we’ve reached the area minimum. 

We’re still losing extent right now. NSIDC is down another 40k to 4.77 million sq km. 

[Vice-Regent]

On 9/8/2021 at 2:54 PM, LibertyBell said:

Hey John, ants and most other insects (including flies and bees) are highly intelligent, it's curious how much power can be packed into a tiny brain.  Nature is quite wondrous.

 

https://www.abc.net.au/science/articles/2015/05/15/4236373.htm

Flies likely feel fear similar to the way that we do, according to a new study that opens up the possibility that flies experience other emotions too.

The finding further suggests that other small creatures — from ants to spiders — may be emotional beings as well.

"No one will argue with you if you claim that flies have four fundamental drives just as humans do: feeding, fighting, fleeing, and mating," says William Gibson, lead author of the study published in the journal Current Biology.

"Taking the question a step further — whether flies that flee a stimulus are actually afraid of that stimulus — is much more difficult," adds Gibson, a postdoctoral fellow at Caltech.

Such a 'stimulus' could be an annoyed person chasing the fly with a swatter, or even a creepy shadow that could mean a threat is imminent.

Afraid of shadows
The researchers used shadows to study how flies reacted to something that could be fear inducing.

Gibson and his team enclosed flies in an arena where the buzzing insects were exposed repeatedly to an overhead shadow. The flies looked startled and, if flying, increased their speed. Occasionally the flies froze in place, a defensive behaviour also observed in the fear responses of rodents.

The shadows even caused hungry flies to leave a food source, when that was presented during another phase of the experiment. It then took time before those same flies would return to their food, suggesting a gradual diminishment of the insects' internal, defensive state. Importantly, the more shadows the flies were exposed to, the longer it took for them to "calm down" and return to the food.

In other words, when flies flee in response to a shadow, it's more than a momentary escape. It's a lasting physiological state comparable to how we experience fear.

Naysayers could claim that this was all just instinctual behaviour with no real underlying depth to it. But even for humans and other higher-on-the-food chain animals, feelings fall into what the researchers call "emotion primitives." These have to do with how nerves, biochemistry and other underlying factors work.

For fear, the first basic characteristic is that the fear is persistent, Gibson said. For example, if a person hears the sound of a gun, the feeling of fear that it provokes will continue for a period of time.

The second characteristic is that fear is scalable - the more gunshots a person hears, the more afraid he or she will become.

The third characteristic of fear, according to the researchers, is that it exists across different contexts.

And fear is also "trans-situational" - once you're afraid, you're more likely to respond in fear to other triggers, such as the clang of a pan, for instance, or a loud knock at the door.

Gibson and his colleagues determined that all of these applied to the flies in the study, strongly suggesting that they do indeed feel the emotion fear as we do.

Other applications
There's more to this research than just learning about flies, the scientists say. It's helping the scientists to understand, in a very fundamental way, what constitutes fear and other emotions in all animals, including humans.

"The argument that this paper makes is that the Drosophila (a type of fly) system may be an excellent model for emotion states due to the relative simplicity of its nervous system, combined simultaneously with the behavioural complexity it exhibits," Gibson explains.

Such a system may make it possible to identify new molecular players involved in the control of emotion states, he says.

Those, in turn, could lead to better treatments for people suffering from nervous disorders, depression and much more.

Related: Pesky flies use fighter jet manoeuvres

https://www.abc.net.au/news/science/2017-02-24/smart-bees-learn-how-to-use-tools-by-watching-others/8297576?section=science

They may have tiny brains, but it turns out that bumblebees can not only learn to use tools by observing others, they can improvise and make the task even easier.

Key points:
Bees were taught how to do a task they would not normally do
They were able to improve on the task after watching another bee complete it
Study shows that bees have cognitive powers way beyond what we thought an insect could have
We knew bees were smart, but this level of brain power has never before been seen in an insect, according to a team of UK scientists writing in the journal Science.

"Our study terminates the idea that small brains constrain insects to have limited behavioural flexibility and only simple learning abilities," said Olli Loukola of Queen Mary University of London.

Dr Loukola said previous research had shown that bees could solve a range of complex tasks, including categorising objects, simple spatial concepts and even counting.

"But these tasks have always resembled those similar to the insect's natural foraging routines," he said.

To take the bees out of their comfort zone, Dr Loukola and his colleagues designed a series of experiments where the bees were taught to move a ball to the centre of a platform, in exchange for a food reward.

How to train a bee
The researchers used a plastic bumblebee to show the bees what to do, until the learners successfully completed the task themselves within five minutes.

But then the team went further by training bees in a set-up with three balls, where the two closest to the centre were superglued to the platform.

These bees were then used as "trainers", fetching the farthest ball in a repeat of the same set-up, with an untrained bee watching.

Remarkably, when those watching bees were then offered a similar scenario on their own — this time with three unglued balls to choose from — they not only succeeded, they tended to choose the closest ball to the centre, improving on the behaviour of the trainer bees.

Bees that were trained by a hidden magnet or got no lesson at all, on the other hand, were much less successful.

It seems that bees do their best learning — and improvising — after watching a fellow bumblebee do the job.

Dr Loukola said the findings showed that the observer bees were not simply copying what they saw; they were taking it on board and improving it.

"This goal-directed behaviour shows an impressive amount of cognitive flexibility, especially for an insect," he said.

He said the bees' capacity to solve complex tasks could help them to survive constantly changing environments.

"However, rapid climate change, habitat loss and the use of pesticides are unfortunately too much, even for the cleverest bumblebees," he said.

Bumblebee loaded with pollen
Bumblebees continue to surprise us with their brain power.(Wikimedia: Tony Willis)
Bees smarter than we give them credit for
Associate Professor Andrew Barron of Macquarie University said the study provided a "convincing argument" that bees could rapidly learn how to do something by watching others.

"That's been very contentious as to whether insects can do that," said Dr Barron, who studies bee brains.

He said the study demonstrated bees were a lot more behaviourally flexible and adaptable than we had given them credit for.

"We are getting an increasing idea about how the structure of the bee brain works. What is continuing to surprise us, is what bees are doing with that brain," he said.

"We wouldn't be surprised to see [this kind of behaviour] in something like a rat, but certainly this is the first demonstration we've got of these forms of behaviour [in insects]," he said.

Dr Barron said the study also provided a different perspective on the human brain.

"For me, the questions is how are they able to achieve this level of behavioural flexibility with a brain that has less than a million neurons?"

"If a bee can do this kind of thing ... with a tiny brain, why is ours so massive?"

https://www.abc.net.au/science/articles/2014/04/11/3983454.htm

Pesky flies use fighter jet manoeuvres
Friday, 11 April 2014Will Dunham
Reuters

A flying fruit fly (Drosophila hydei).
The flies showed that they could roll on their sides by upwards of 90 degrees, sometimes flying almost upside down (Source: Floris van Breugel and Florian Muijres/)

Related Stories
Video games test bees' visual smarts, Science Online, 18 Mar 2014
Fornicating flies attract hungry bats, Science Online, 24 Jul 2012
The intricate world of flies, Science Online, 19 May 2009
What does a tiny fruit fly have in common with the world's most advanced fighter jets like the US Air Force's F-22 Raptor? More than you might think.

Scientists using video cameras to track a fly's aerial manoeuvres found the insect employs astonishingly quick mid-air banked turns to evade predators much like a fighter jet executes to elude an enemy.

Their study, published in the journal Science, documents aerial agility in fruit flies such as the capacity to begin to change course in less than one one-hundredth of a second.

The fact that flies are airborne acrobats should not surprise anyone who has ever swung a flyswatter at one, only to watch the little insects easily escape.

The researchers at the University of Washington synchronised three high-speed cameras operating at 7,500 frames a second to learn the secrets of what the flies do to make themselves so elusive.

They tracked the mid-air wing and body motion of the fruit fly species Drosophila hydei, which is about the size of a sesame seed, inside a cylindrical flight chamber after the insects were shown an image that suggested an approaching predator.

The flies produced impressive escape responses, almost instantaneously rolling their bodies like a military jet in a banked turn to steer away. While executing the turn, the flies showed that they could roll on their sides by upwards of 90 degrees, sometimes flying almost upside down.

"They generate a rather precise banked turn, just like an aircraft pilot would, to roll the body and generate a force to take them away from the threat," says University of Washington biology Professor Michael Dickinson, who led the study.

"That happens very quickly. And it's generated with remarkably subtle changes in wing motion. We were pretty astonished by how little they have to do with their wing motion to generate these very precise manoeuvres," he says.

Ancient reflexes
The fly flaps its wings about 200 times a second, and in almost a single wing beat can reorient its body to manoeuvre away from the threat and continue to accelerate, Florian Muijres, says another of the researchers.

"I suspect that these are very ancient reflexes," Dickinson adds. "Very shortly after insects evolved flight, other insects evolved flight to eat them. Circuits for detecting predators are very, very ancient. But this one is just being implemented in a high-performance flight machine."

A lot of light was needed to accommodate the cameras' extraordinarily high shutter speeds, but because a fly would be blinded by the necessary amounts of normal light, the researchers used very bright infrared lights. Like people, fruit flies do not see infrared light.

"I've always been fascinated by flies. Everybody thinks that they have a simple nervous system, but I think it's exactly the opposite. They just have a really tiny one. But it's incredibly compact. They do so much with just this brain the size of a salt grain," Dickinson says.
 

I hope to god that nobody lived their lives thinking animals were not emotional beings. Well you learn something new every day.

Our destination is arriving before us but are we willing to accept the error of our ways or depart this exercise in futility?

 

[LibertyBell]

10 hours ago, Vice-Regent said:

I hope to god that nobody lived their lives thinking animals were not emotional beings. Well you learn something new every day.

Our destination is arriving before us but are we willing to accept the error of our ways or depart this exercise in futility?

 

Amazingly some very anthropocentric people who should have known better thought animals were no different from robots for a long time and used it to justify their unethical treatment of them.

 

[bluewave]

This will be the tenth year since 2007 with a daily NSIDC minimum extent in the 4s. Two years finished below 4 million sq km and three slightly above 5 million sq km. Following 2007, no year has been able to finish above 6 million sq km in a much warmer Arctic.

[ORH_wxman]

I think the area min has been reached. It increased another 27k today. We’re now over 200k above the 9/1 minimum. 

[bdgwx]

The NSIDC site now has an http link for their data. This is useful since many browsers no longer support FTP.

https://masie_web.apps.nsidc.org/pub/DATASETS/NOAA/G02135/seaice_analysis/

[donsutherland1]

Arctic sea ice extent was 4.648 million square kilometers on September 11 on JAXA. The minimum extent is likely near or imminent, but the Larry's impact is a wildcard. The 25th percentile (lowest) based on the August 31 value was 4.610 million square kilometers.

[LibertyBell]

5 hours ago, donsutherland1 said:

Arctic sea ice extent was 4.648 million square kilometers on September 11 on JAXA. The minimum extent is likely near or imminent, but the Larry's impact is a wildcard. The 25th percentile (lowest) based on the August 31 value was 4.610 million square kilometers.

Larry made landfall as an 80 mph true hurricane near St John's, Labrador- Don is that the furthest north landfall a hurricane has ever made?  I heard it will drop 4 feet of snow on Greenland?

 

[donsutherland1]

6 hours ago, LibertyBell said:

Larry made landfall as an 80 mph true hurricane near St John's, Labrador- Don is that the furthest north landfall a hurricane has ever made?  I heard it will drop 4 feet of snow on Greenland?

 

I am not sure about the pure hurricane vs. post-tropical/transitioning hurricane, as the charts don't distinguish between them.

Greenland picked up 10 gigatons of mass yesterday from the Larry-induced blizzard. That was, by far, a record for this early in the season.

[donsutherland1]

Arctic sea ice extent fell further to 4.613 million square kilometers (JAXA). The last year with a higher minimum was 2014 when the minimum extent was 4.884 million square kilometers.

[rclab]

1 hour ago, donsutherland1 said:

I am not sure about the pure hurricane vs. post-tropical/transitioning hurricane, as the charts don't distinguish between them.

Greenland picked up 10 gigatons of mass yesterday from the Larry-induced blizzard. That was, by far, a record for this early in the season.

Good morning Don, Liberty. Even as my personal time ebbs, I think of equations and the balance they seek to describe. If a true p-t/hurricane hitting Labrador and 10 gigs-tons of frozen mass, descending on Greenland, is an example, my fear for the direction/results of balance will continue to grow. As always …..

[LibertyBell]

3 hours ago, donsutherland1 said:

I am not sure about the pure hurricane vs. post-tropical/transitioning hurricane, as the charts don't distinguish between them.

Greenland picked up 10 gigatons of mass yesterday from the Larry-induced blizzard. That was, by far, a record for this early in the season.

How is added mass measured?  That's fascinating!

[donsutherland1]

2 hours ago, LibertyBell said:

How is added mass measured?  That's fascinating!

It’s estimated from satellite gravity measurements. Here’s a paper that explains, in part, about the process. More complex measurements take into consideration changes in ice, run-off, etc.

https://escholarship.org/content/qt6jh183rg/qt6jh183rg.pdf

 

[LibertyBell]

3 minutes ago, donsutherland1 said:

It’s estimated from satellite gravity measurements. Here’s a paper that explains, in part, about the process. More complex measurements take into consideration changes in ice, run-off, etc.

https://escholarship.org/content/qt6jh183rg/qt6jh183rg.pdf

 

Is there a way to equate this to snowfall measurements?

I wonder if we can now confirm record snow depths using this method?

Not to mention measure new record high and record low temps from remote parts of the world where there are few sensors (like remote parts of Antarctica that might be colder than Vostok?)

 

[Taylorsweather]

It may take several days longer to be sure, but Jaxa extent minimum may have been reached two days ago at 4.612 million km2.  We currently stand 54,000 km2 above that number after two straight days of increase.

[donsutherland1]

On 7/30/2021 at 8:49 PM, Weatherdude88 said:

Slater Probabilistic Sea Ice extent showing 5.15 million square kilometers on September 18th. It's very possible NSIDC sea ice extent minimum will be greater than 5 million square kilometers, given current NSIDC area and compaction at high latitudes. Remember, we are ahead of 2013 in area for the date. 2013 had a minimum of 5.10 million square kilometers of extent.

Just as had been the case last year, the Slater model performed horribly. Had one taken the mean 2010-2020 decline from the date the model forecast was generated, one would have had a vastly better idea of minimum extent.

That figure was 4.4 million square kilometers (JAXA). The SIA had an implied minimum of 5.15 million square kilometers.

Now that Arctic sea ice extent has increased for 3 consecutive days, it is likely that the 9/12 figure of 4,612,915 square kilometers will be the 2021 minimum.

That will be the highest minimum extent since 2014 when the minimum extent was 4,884,120 square kilometers. The last figure at or above 5 million square kilometers was more than a decade ago in 2009.

 

[bluewave]

We now have a new AI based sea ice forecasting system.The paper was just published in late August. So their first official forecast was issued a few weeks ago on the ARCUS site. The September daily minimum was very close to their September average monthly forecast. The September average extent will come in a little higher which is always the case due to the higher average extent in early and late September. 

Name of contributor or name of contributing organization:
IceNet1

https://www.arcus.org/files/sio/32360/icenet1_2021_sio_august_individual_report.pdf

a) Pan-Arctic September extent prediction in million square kilometers.
4.75

IceNet is a sea ice forecasting AI system which predicts monthly-averaged sea ice probability (SIP; probability of sea ice concentration > 15%) up to 6 months ahead at 25 km resolution on an EASE2 grid. IceNet is based on a deep learning U-Net architecture, and has been trained on climate simulations (CMIP6) covering 1850-2100 and observational data (OSI-SAF SIC and ERA5) from 1979-2011. IceNet’s monthly-averaged inputs comprise SIC, 11 climate variables, statistical SIC forecasts, and metadata. IceNet is introduced in the following pre-print, with the study soon to be published in Nature Communications: https://doi.org/10.31223/X5430P. IceNet was also presented at the Oxford ML and Physics Seminar Series: https://youtu.be/JAKWhEU09Xo.
Brief explanation of Outlook method (using 300 words or less).
At each 25x25 km ocean grid cell in the Arctic and at each forecast lead time from 1 to 6 months ahead, IceNet produces a probability that the SIC will be less than 15% (no ice), between 15% and 80% (marginal ice), or above 80% (full ice). To compute the SIP map for this SIO submission, we sum the probability of the two ice classes to obtain P(SIC > 15%). IceNet comprises 25 different U-Net models, whose output SIPs are averaged to produce the final SIP forecast. To compute the SIE, we sum the area of grid cells whose SIP > 0.5.

 

 

[Taylorsweather]

On 9/15/2021 at 6:57 AM, Taylorsweather said:

It may take several days longer to be sure, but Jaxa extent minimum may have been reached two days ago at 4.612 million km2.  We currently stand 54,000 km2 above that number after two straight days of increase.

Extent is now 92,000 km2 above its low three days ago.  So minimum may have occurred on 9/13.

[Typhoon Tip]

17 hours ago, Taylorsweather said:

Extent is now 92,000 km2 above its low three days ago.  So minimum may have occurred on 9/13.

I'm curious how much of these seasonal nadir stops are guided by the vagaries of the AO index leading... 

That's obviously a very complex question.  Multi-faceted factoring, most likely, determines.   Such as momentum under air - as in, SST and ice thickness, be it solar sensitivity ... cloud permutations... and holy hell.

But, perhaps the general negative versus positive index mode may encapsulate and thus correlate in general.  A season's stop-loss takes place whether higher or lower AO.  

Positive modes of the AO are warm for mid latitudes, but are cold inside the arctic domain.  Vice versa for negative index modes.   We all know that...  Those that don't want the Earth to die from GW ... would rather the summer be a +AO mode, and the winter to be oscillating between the ( - ) and ( + ) states...and on and sardonic so on.. lol.

But more seriously, when using the CPC history the curve of the AO spent the ballast of the summer positive. It did briefly go negative around the first of September, but only briefly so... If then considering momentum and transience amid the index, it may not be enough to significantly deviate from an established seasonal vector to keep the domain conserved.. I mean comparing over recent years .. perhaps 'offsetting' the bottoming momentum of the physical ice from realizing how far it 'could have' plumbed.  

 

[ORH_wxman]

On 9/16/2021 at 10:02 AM, donsutherland1 said:

Just as had been the case last year, the Slater model performed horribly. Had one taken the mean 2010-2020 decline from the date the model forecast was generated, one would have had a vastly better idea of minimum extent.

That figure was 4.4 million square kilometers (JAXA). The SIA had an implied minimum of 5.15 million square kilometers.

Now that Arctic sea ice extent has increased for 3 consecutive days, it is likely that the 9/12 figure of 4,612,915 square kilometers will be the 2021 minimum.

That will be the highest minimum extent since 2014 when the minimum extent was 4,884,120 square kilometers. The last figure at or above 5 million square kilometers was more than a decade ago in 2009.

 

FWIW, the slater model is predicting NSIDC extent, not JAXA. NSIDC tends to be a bit higher than JAXA....often 100k to 200k higher on the min.

It still performed poorly this year, though. Just not quite as bad as when compared to JAXA figures.

[LongBeachSurfFreak]

On 9/16/2021 at 11:33 AM, bluewave said:

We now have a new AI based sea ice forecasting system.The paper was just published in late August. So their first official forecast was issued a few weeks ago on the ARCUS site. The September daily minimum was very close to their September average monthly forecast. The September average extent will come in a little higher which is always the case due to the higher average extent in early and late September. 

Name of contributor or name of contributing organization:
IceNet1

https://www.arcus.org/files/sio/32360/icenet1_2021_sio_august_individual_report.pdf

a) Pan-Arctic September extent prediction in million square kilometers.
4.75

IceNet is a sea ice forecasting AI system which predicts monthly-averaged sea ice probability (SIP; probability of sea ice concentration > 15%) up to 6 months ahead at 25 km resolution on an EASE2 grid. IceNet is based on a deep learning U-Net architecture, and has been trained on climate simulations (CMIP6) covering 1850-2100 and observational data (OSI-SAF SIC and ERA5) from 1979-2011. IceNet’s monthly-averaged inputs comprise SIC, 11 climate variables, statistical SIC forecasts, and metadata. IceNet is introduced in the following pre-print, with the study soon to be published in Nature Communications: https://doi.org/10.31223/X5430P. IceNet was also presented at the Oxford ML and Physics Seminar Series: https://youtu.be/JAKWhEU09Xo.
Brief explanation of Outlook method (using 300 words or less).
At each 25x25 km ocean grid cell in the Arctic and at each forecast lead time from 1 to 6 months ahead, IceNet produces a probability that the SIC will be less than 15% (no ice), between 15% and 80% (marginal ice), or above 80% (full ice). To compute the SIP map for this SIO submission, we sum the probability of the two ice classes to obtain P(SIC > 15%). IceNet comprises 25 different U-Net models, whose output SIPs are averaged to produce the final SIP forecast. To compute the SIE, we sum the area of grid cells whose SIP > 0.5.

 

 

Great find Bluewave. Tremendous work by Tom Anderson. With continued learning accuracy will increase further. I’m not sure there is much hope for indigenous communities in regards to sea ice however. Villages are literally falling into the sea as a result of erosion caused by the lack of sea ice. Talk about disparity’s in climate change effects on given community’s.  

[donsutherland1]

4 hours ago, ORH_wxman said:

FWIW, the slater model is predicting NSIDC extent, not JAXA. NSIDC tends to be a bit higher than JAXA....often 100k to 200k higher on the min.

It still performed poorly this year, though. Just not quite as bad as when compared to JAXA figures.

Thanks. It still missed badly on NSIDC both last year and this year.

[LibertyBell]

3 hours ago, LongBeachSurfFreak said:

Great find Bluewave. Tremendous work by Tom Anderson. With continued learning accuracy will increase further. I’m not sure there is much hope for indigenous communities in regards to sea ice however. Villages are literally falling into the sea as a result of erosion caused by the lack of sea ice. Talk about disparity’s in climate change effects on given community’s.  

it's on governments to give land to these communities.  I also believe that people living in oceanic nations need to be taken in by other nations and given land to live on

 

[ORH_wxman]

On 7/2/2021 at 9:24 AM, ORH_wxman said:

Given we're now past 7/1, it is time for the annual forecast.

Quick update on standings:

2020: -430k

2019: -380k

2018: +390k

2017: +70k

2016: -180k

2015: +190k

2014: +320k

2013: +390k

2012: -590k

2011: -140k

2010: -310k

2009: +710k

2008: +280k

2007: -330k

 

 

You can see last year's forecast here:

 

And here is last year's verification:

 

As for 2021.....below is what the final area would be if we followed the path of every other year from here on out. An example is that if we followed the path of 2012 from here on out and lost another 4.3 million sqkm of ice like that year did post-7/1, then we would finish at 2.7 million sq km. The reason the forecasts are pretty accurate is that area loss post-7/1 is pretty stable over time going back to 1979. There has been a bias toward a little bit higher in the post-2007 world, but it is much smaller than the differences we see prior to July 1st (i.e., most of the area loss can be explained by what happens prior to 7/1.)

 

 

 

Two things stick out on the graph....one, is that any minimum above 4.00 million sq km is basically impossible no matter which path we follow. Nevermind that we haven't had an area min above 4.0 million sq km since 2006 anyway, but there isn't even a realistic shot at one this year like perhaps was plausible in years like 2014.

Secondly, the chance at a new record minimum is basically impossible too. The two largest melt years post-7/1 were 1989 and 2016. You can see following both of their paths still only produces a min around 2.5 million sq km....well above the record-low 2.23 million sq km minimum in 2012.

 

Given that information, I will use the post-2007 average as my baseline. I might even skew a little on the high side of that unlike last year because the forecast is quite stormy over the arctic basin for the foreseeable future. The EPS have a pretty strong vortex over the pole through mid-July which is wasting what's left of prime insolation season up there.

 

Taking a post-2007 average result post-7/1 purely at face value would yield a minimum of 2.9 sq km in 2021. I'll skew just a touch higher than that based on the forecast and current distribution of the ice. So for an area minimum, I'll forecast 3.0 million sqkm +/- 300k. That would place 2021 around 8th lowest.

Sea ice extent is a bit more fickle since compaction plays a larger part unlike area. But I'll go 4.3 million sq km on NSIDC extent +/- 500k. I have a larger range on the extent min since it has a much higher standard deviation than area.

 

I believe the extent minimum has been reached now that we are almost 140k higher on NSIDC than the 9/13 min of 4.7 million sq km...and the area minimum was reached on 9/1.

So time for verification based on the predictions from June NSIDC area.....

The minimum area was 3.17 million sq km on 9/1. This places 2021 as the 11th lowest area minimum. The more unique aspect of the area minimum was that it was the 2nd earliest area min on record. Only 1992 had an earlier min than the 9/1 date this year....the min that year was 8/31. The forecast above predicted 3 million sq km so I was a little low on my prediction but well within the error bars. I would consider this a pretty strong forecast.

The minimum NSIDC extent was 4.7 million sq km on 9/13. This ranks 12th lowest on record. My prediction of 4.3 million sq km was too low but still within the wider 500k error bars. Extent is notoriously harder to predict than area. The melt conditions in May/June correctly predicted this wouldn't be a top 5 melt season, but somewhat underestimated how much ice would survive. The favorable conditions in late July and August likely aided in some of that extra retention not able to be foreseen at the end of June. I'd still consider it a decent forecast but not as good as the area forecast was.

 

These figures may be revised slightly by NSIDC in the future as is often the case, but the overall standing of 2021 isn't likely to change much at all from any revisions. They are usually very minor.

[forkyfork]

almost time for 88 to come back and post about record gains

[bluewave]

Multiyear ice finishes at 2nd lowest on record with extent in 12th place.
 

 

 

[Weatherdude88]

On 10/6/2021 at 11:33 AM, bluewave said:

Multiyear ice finishes at 2nd lowest on record with extent in 12th place.
 

 

 

2020 was the second lowest sea ice extent minimum value on record. This is why 2021 northern hemisphere multi year ice ranked as second lowest at minimum (0 - 1 year).

Now that the freezing season has started, the remaining ice is now all multi year ice (greater than 1 year old). So if we finish next melting season in a similar place, multi year ice may be in approximately 12th place. 

The above statement, highlights the recovery from the 2020 melting season VS. the 2021 melting season.

[bluewave]

8 hours ago, Weatherdude88 said:

2020 was the second lowest sea ice extent minimum value on record. This is why 2021 northern hemisphere multi year ice ranked as second lowest at minimum (0 - 1 year).

Now that the freezing season has started, the remaining ice is now all multi year ice (greater than 1 year old). So if we finish next melting season in a similar place, multi year ice may be in approximately 12th place. 

The above statement, highlights the recovery from the 2020 melting season VS. the 2021 melting season.

The record winds during the winter transported the MYI into the Beaufort giving it more chance to melt out during the summer. 
 

https://nsidc.org/arcticseaicenews/

Despite September total ice extent being high compared to recent years, the amount of multiyear ice as assessed from ice age (Figure 5e) reached a near-record low, with an extent of only 1.29 million square kilometers (498,000 square miles), just slightly above the value of 1.27 million square kilometers (490,000 square miles) at the end of the 2012 melt season.