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Author Topic: Albedo-Warming Potential  (Read 50253 times)

Phoenix

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Re: Albedo-Warming Potential
« Reply #150 on: July 16, 2020, 06:37:54 AM »
Perhaps Nico can weigh and explain how to interpret some of the figures on his site. See the attached link...

https://cryospherecomputing.tk/awp-region.html

For the CAB chart on the bottom right, it looks like the annual solar input potential is ~ 2,600 MJ / m2 and the actual input  (if I understand the chart correctly) is ~ 500-600 MJ / m2. This would presumably be net of both albedo reflection and also cloud reflection ??

The charts are depicting actual albedo warming in the CAB as ~ 25% of the ice free potential implying 75% average reflection. I guess if I look at those charts a lot, I should try to know exactly what they mean. There is some distance to be reconciled here. Perhaps estimated cloudiness is the difference?
« Last Edit: July 16, 2020, 06:48:07 AM by oren »

sedziobs

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Re: Albedo-Warming Potential
« Reply #151 on: July 16, 2020, 07:10:16 AM »
This would presumably be net of both albedo reflection and also cloud reflection ??

The charts are depicting actual albedo warming in the CAB as ~ 25% of the ice free potential implying 75% average reflection. I guess if I look at those charts a lot, I should try to know exactly what they mean. There is some distance to be reconciled here. Perhaps estimated cloudiness is the difference?

Look at the y-axis title: clear sky absorption. Clouds are not factored in, which is why it's called Warming "Potential."

In the CAB, it looks like actual absorption is about 20% of ice free absorption until mid-May, which makes sense for 80% snow-covered ice albedo. Then the decadal values start to diverge as melt pond and open water fractions vary. I suspect that actual summer values are slightly underestimated as a result of albedo assumptions for bare ice and melt ponds.

oren

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Re: Albedo-Warming Potential
« Reply #152 on: July 16, 2020, 07:16:41 AM »
It's a result of an assumption about albedo which is true for part of the season but not for other parts of it. Remember the (excellent) tool is for comparison between years, mainly quantifying the latitude and location of open water and the amount of insolation it can receive.

Phoenix

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Re: Albedo-Warming Potential
« Reply #153 on: July 16, 2020, 03:39:55 PM »
It's a result of an assumption about albedo which is true for part of the season but not for other parts of it. Remember the (excellent) tool is for comparison between years, mainly quantifying the latitude and location of open water and the amount of insolation it can receive.

I see what you are saying. But if the tool is really only useful for accurately quantifying the open water AWP and not the areas which are covered by sea ice, it's not very useful for measuring what's going on in the CAB. 

I appreciate your taking the time. Math helps to drill down to the variables in question.

igs

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Re: Albedo-Warming Potential
« Reply #154 on: July 16, 2020, 06:25:37 PM »
It's a result of an assumption about albedo which is true for part of the season but not for other parts of it. Remember the (excellent) tool is for comparison between years, mainly quantifying the latitude and location of open water and the amount of insolation it can receive.

I see what you are saying. But if the tool is really only useful for accurately quantifying the open water AWP and not the areas which are covered by sea ice, it's not very useful for measuring what's going on in the CAB. 

I appreciate your taking the time. Math helps to drill down to the variables in question.


A potiential does not claim to be a good tool for measuring but to compare seasons which is what @Oren just said and there in fact wouldn't be much useful to add to that.

oren

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Re: Albedo-Warming Potential
« Reply #155 on: July 16, 2020, 07:49:56 PM »
I will add, most years albedo, and cloudiness, average out, and since open water has a much lower albedo than anything else, and is often found in more southern latitudes where insolation is accumulated over a longer season, the tool is quite useful even though it skips some of the details. In a weird year such as this, with both low albedo and low cloudiness especially in the center of the CAB, the comparison misses too much of what makes the year unique, but that does not mean the comparison is not useful or has not been useful in the past.

sedziobs

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Re: Albedo-Warming Potential
« Reply #156 on: July 16, 2020, 08:00:46 PM »
Similarly, Slater's model struggles with this season as well because it knows that compact ice in the CAB has historically not melted by September. That will be true until it isn't. All tools have their limits.

Phoenix

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Re: Albedo-Warming Potential
« Reply #157 on: July 16, 2020, 08:28:50 PM »
I will add, most years albedo, and cloudiness, average out, and since open water has a much lower albedo than anything else, and is often found in more southern latitudes where insolation is accumulated over a longer season, the tool is quite useful even though it skips some of the details. In a weird year such as this, with both low albedo and low cloudiness especially in the center of the CAB, the comparison misses too much of what makes the year unique, but that does not mean the comparison is not useful or has not been useful in the past.

Fair enough. Understanding is enhanced by trying to reconcile seemingly conflicting or ambiguous points. In this case about albedo.

You have made a persuasive case which helps to reconcile the ambiguity. Thank you.

"Tell me I forget, teach me I remember, involve me I learn" ~ Benjamin Franklin

morganism

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Re: Albedo-Warming Potential
« Reply #158 on: December 03, 2020, 10:02:26 AM »
Deep Future Climate on Earth: effects of tectonics, rotation rate, and insolation

https://www.essoar.org/doi/10.1002/essoar.10501348.1

https://www.centauri-dreams.org/2020/12/02/deep-future-the-next-supercontinent/

"We know that Earth’s continents used to be packed into a single large land mass called Pangaea, which is thought to have broken apart about 200 million years ago as tectonic plates shifted. Interestingly, we can expect a remote future in which the continents will have once again come together

"The first, occurring in the modeling in about 200 million years, is a merging of all continents except Antarctica around the north pole, forming the supercontinent ‘Amasia.’

The second: The formation of the supercontinent ‘Aurica,’ as all the continents come together around the equator in about 250 million years. The effects are significantly different. The formation of Amasia around the north pole produces a planet about 3 degrees Celsius cooler than the one resulting from the formation of Aurica around the equator. What happens is that the movement of heat from the equator to both poles is disrupted with all the land around the poles.

With heat not being conveyed as efficiently from equator to pole, the poles become colder and remain covered in ice all year long, reflecting significant heat into space. Amasia, according to Way, produces “a lot more snowfall. You get ice sheets, and you get this very effective ice-albedo feedback, which tends to lower the temperature of the planet.”

You also get lower sea levels in the Amasia scenario, with more water trapped in the ice caps. Less land is available for agriculture in a supercontinent with predominantly snowy conditions."


kassy

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Re: Albedo-Warming Potential
« Reply #159 on: December 07, 2020, 01:40:17 PM »
Tealight posted a thread about the future of his website in The Rest. Since not everyone visits that forum here is the link:
https://forum.arctic-sea-ice.net/index.php/topic,3350.0.html
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.