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Author Topic: Albedo-Warming Potential  (Read 31581 times)

oren

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Re: Albedo-Warming Potential
« Reply #100 on: April 27, 2019, 07:45:24 PM »
Thanks a lot Tealight.

gerontocrat

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Re: Albedo-Warming Potential
« Reply #101 on: April 27, 2019, 08:04:46 PM »
Here are 2 area graphs,

The High Arctic 7 seas as defined by Tealight,

All 14 Arctic Seas per NSIDC.

As you can see, as far as the High Arctic is concerned, melting has not really started yet.
It also shows that the summer melt produced relatively steeper decline in these central seas.
« Last Edit: April 27, 2019, 08:14:05 PM by gerontocrat »
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kiwichick16

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Re: Albedo-Warming Potential
« Reply #102 on: April 28, 2019, 06:55:03 AM »
losing  a million  sq kms per decade @ at the annual minimum in September.......at that rate the Arctic will be ice free sometime in the 2030's  ....if not before

Stephan

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Re: Albedo-Warming Potential
« Reply #103 on: April 28, 2019, 01:02:03 PM »
Tealight - thanks a million for all the work you've done
Gerontocrat - thanks for the ice cover charts to support Tealight's evaluation.

Two 'likes' earned

Tealight

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Re: Albedo-Warming Potential
« Reply #104 on: May 01, 2019, 01:05:08 AM »
Just in time before the May melt ponds start I created the regional anomaly charts. Just like last year almost all of the early accumulated AWP anomaly comes from the Bering Sea, but this year none of the regions is in the negative.

https://cryospherecomputing.tk/NRTawp

dosibl

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Re: Albedo-Warming Potential
« Reply #105 on: May 02, 2019, 04:54:43 PM »
No surprise that we're tracking to get a similar anomaly in the Bering as last year, iirc last years ~250 mj/m2 was basically double any prior year.

Tealight, my understanding of the 'potential' part of AWP is that the calculation doesn't account for weather, correct? A cloudy season and a sunny season with similar extent would produce similar AWP numbers but would experience different actual warming?

oren

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Re: Albedo-Warming Potential
« Reply #106 on: May 03, 2019, 12:52:15 AM »
No surprise that we're tracking to get a similar anomaly in the Bering as last year, iirc last years ~250 mj/m2 was basically double any prior year.

Tealight, my understanding of the 'potential' part of AWP is that the calculation doesn't account for weather, correct? A cloudy season and a sunny season with similar extent would produce similar AWP numbers but would experience different actual warming?
2019 is actually tracking somewhat higher, at 200 instead of 175.

My understanding of the 'P' is the same.

Tealight

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Re: Albedo-Warming Potential
« Reply #107 on: May 03, 2019, 02:21:56 AM »
No surprise that we're tracking to get a similar anomaly in the Bering as last year, iirc last years ~250 mj/m2 was basically double any prior year.

Tealight, my understanding of the 'potential' part of AWP is that the calculation doesn't account for weather, correct? A cloudy season and a sunny season with similar extent would produce similar AWP numbers but would experience different actual warming?

You are right that it doesn't account for weather and doesn't calculate actual warming. The data presented here is just a model to rank years against each other instead of a daily or monthly minimum number. It also quantifies the actual surface albedo change in the Arctic. However, the underlying physics are good enough for real applications. Maybe I can give more information tomorrow.

Darvince

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Re: Albedo-Warming Potential
« Reply #108 on: May 05, 2019, 07:11:02 PM »
I note that 2016 despite its very strong early start ended up with a lower AWP anomaly than 2012 in the high Arctic. I guess that's the power of cloudy weather for you.

Tealight

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Re: Albedo-Warming Potential
« Reply #109 on: May 05, 2019, 08:27:26 PM »
Very popular here are the sea ice minimum and maximum polls guessing the correct sea ice extent in millions of square kilometer. A more scientific oriented version of it is the Sea Ice Prediction Network: https://www.arcus.org/sipn
This year was the second time they made a trial run to forecast the Antarctic summer minimum and I participated (as Nico Sun) with a forecast model derived from this Albedo-Warming Potential model. The underlying physics are the same. The major difference is that instead of accumulating an energy value in a grid cell, this energy is used to calculate the sea ice thickness loss. Additionally I added an outgoing infrared radiation variable to get an actual energy balance.

With the post season report released I can proudly claim victory not only in overall area values, but also on a regional scale with the lowest error over the entire 3 month forecasting period. This is in part thanks to the real world usefulness of the AWP model and in part due to the submission deadline of 1st December. Some other team's can only run their models at the beginning of every month and had to use October data for their model initialization. I attached the two most relevant figures, but recommend to read the whole report.

Full 2018-2019 post season report
http://www.climate.be/users/fmasson/SIPN-South_2018-2019_postseason.pdf

General SIPN south website
http://acecrc.org.au/sipn-south/


Sea Ice Loss Formula of the forecast model:

Ed = MJ_inlat,day x (1 - SIC) - MJ_out
z = Ed / Efusion

Ed = Melt energy per day
MJ_in = incoming solar radiation per m2
MJ_out = outgoing infrared emmision per m2
SIC = sea ice concentration
z = thickness loss in m
Efusion = Enthalpy of fusion per m3
« Last Edit: May 05, 2019, 10:59:20 PM by Tealight »

magnamentis

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Re: Albedo-Warming Potential
« Reply #110 on: May 05, 2019, 08:34:10 PM »
I note that 2016 despite its very strong early start ended up with a lower AWP anomaly than 2012 in the high Arctic. I guess that's the power of cloudy weather for you.

i think that's because there was way more open water in the CAB in 2012 at the end of the melting seasons hence AWP is somehow logically higher under those conditions and will be again once such a state has been reached
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oren

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Re: Albedo-Warming Potential
« Reply #111 on: May 05, 2019, 08:55:52 PM »
Well done Tealight/Nico!

gerontocrat

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Re: Albedo-Warming Potential
« Reply #112 on: May 05, 2019, 09:39:44 PM »
So Nico Sun gets the medal. Will Tealight get upset ?
Will they send rude letters to the science journals about each other?

And by the way, now the regional Arctic models are up and running, with the key separating out of the high Arctic seas, will he or him or they enter the lists on foreasting the Arctic sea ice minimum?

Tealight, you derive AWP using sea ice area and then use this as a basis to calculate the energy available to reduce sea ice thickness ? How do you translate reduced thickness into resulting sea ice area and extent? A sea might have remaining ice piled up in one area  or spread out giving a higher extent value due to varying winds and currents?

Ps: An impressive piece of work. What with the work on glaciers as well - stunning.
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bbr2314

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Re: Albedo-Warming Potential
« Reply #113 on: May 05, 2019, 10:11:24 PM »
So Nico Sun gets the medal. Will Tealight get upset ?
Will they send rude letters to the science journals about each other?

And by the way, now the regional Arctic models are up and running, with the key separating out of the high Arctic seas, will he or him or they enter the lists on foreasting the Arctic sea ice minimum?

Tealight, you derive AWP using sea ice area and then use this as a basis to calculate the energy available to reduce sea ice thickness ? How do you translate reduced thickness into resulting sea ice area and extent? A sea might have remaining ice piled up in one area  or spread out giving a higher extent value due to varying winds and currents?

Ps: An impressive piece of work. What with the work on glaciers as well - stunning.
Tealight and Nico Sun are the same person...

Tor Bejnar

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Re: Albedo-Warming Potential
« Reply #114 on: May 05, 2019, 11:17:48 PM »
Ever have an agrument all by yourself?
 ::) :-\
Arctic ice is healthy for children and other living things.

Tealight

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Re: Albedo-Warming Potential
« Reply #115 on: May 05, 2019, 11:18:23 PM »
Thanks everyone. I can confirm it feels good to beat major international organisations like NASA, MetOffice and ecmwf.

Tealight, you derive AWP using sea ice area and then use this as a basis to calculate the energy available to reduce sea ice thickness ? How do you translate reduced thickness into resulting sea ice area and extent? A sea might have remaining ice piled up in one area  or spread out giving a higher extent value due to varying winds and currents?

Technically I keep track of two sea ice concentration values. One to calculate the melt (using SIC from previous years) and another calculated from thickness. The second one is the final model output. The additional thickness step makes the model more robust against flashes of low SIC like short term melt ponds.

For the Antarctic I used the following formula to get the best results:
SIC(%) = (Thickness(m)^1.3) / 0.0155

Thickness(m)   SIC value (%)
1.4   100
1.25   86
1   65
0.75   44
0.5   26
0.25   11
0   0

anything over 1.4m stays at 100% SIC.

PaulPassmore

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Re: Albedo-Warming Potential
« Reply #116 on: May 10, 2019, 04:17:20 PM »
Quote
No surprise that we're tracking to get a similar anomaly in the Bering as last year, iirc last years ~250 mj/m2 was basically double any prior year.

Tealight, my understanding of the 'potential' part of AWP is that the calculation doesn't account for weather, correct? Maybe this website https://edubirdie.com/math-problem-solver could do this calculation? A cloudy season and a sunny season with similar extent would produce similar AWP numbers but would experience different actual warming?

It's weird that calculations are so different every year. It seems like main rules are changing all the time.

b_lumenkraft

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Re: Albedo-Warming Potential
« Reply #117 on: May 11, 2019, 07:37:13 AM »
It's weird that calculations are so different every year. It seems like main rules are changing all the time.

Well, it's not that weird, this is a highly complex system after all.

Hello and welcome to the forum Paul.

gerontocrat

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Re: Albedo-Warming Potential
« Reply #118 on: May 11, 2019, 12:49:07 PM »
It's weird that calculations are so different every year. It seems like main rules are changing all the time.

Well, it's not that weird, this is a highly complex system after all.

Hello and welcome to the forum Paul.
The basic laws of physics underlying the calculations do not change. The rules for calculations only change if studies have proved better algorithms. When that happens, the new calculations are applied to all previous data to ensure the record is consistent.

What does change is the weather and behaviour of the oceans that can completely change the pattern of sea ice melt and freeze sea by sea.

Chaos Theory
Edward Lorenz was an early pioneer of the theory. His interest in chaos came about accidentally through his work on weather prediction in 1961.

Welcome to chaos, Paul.
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jai mitchell

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Re: Albedo-Warming Potential
« Reply #119 on: May 16, 2019, 08:36:15 PM »
any analysis of the current impact of albedo forcing due to seasonal sea ice loss during the satellite period should be compared with regional ice loss impacts not arctic basin impacts,  this is due to the variable seasonal solar radiation which maxes at the summer solstice and the retreat of sea ice from the periphery during this time.

The only good study I have found on this was looking at the Beaufort Sea by NASA

https://earthobservatory.nasa.gov/images/84930/the-arctic-is-absorbing-more-sunlight

Quote
When averaged over the entire Arctic Ocean, the increase in absorbed solar radiation is about 10 Watts per square meter. This is equivalent to an extra 10-watt light bulb shining continuously over every 10.76 square feet of Arctic Ocean for the entire summer. Regionally, the increase is even greater, Loeb noted. Areas such as the Beaufort Sea, which has experienced the some of the most pronounced decreases in sea-ice coverage, show a 50 watts per square meter increase.

This is necessary because future sea ice loss impacts during the summer will grow to over 5-fold of the current forcing (determined to be some percentage of 25% of total CO2 forcing around at 2014. 

This large regional forcing will produce rapid changes in the Arctic, especially as we move toward June 21 Summer sea ice loss.

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iceman

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Re: Albedo-Warming Potential
« Reply #120 on: May 18, 2019, 03:55:04 PM »
any analysis of the current impact of albedo forcing due to seasonal sea ice loss during the satellite period should be compared with regional ice loss impacts not arctic basin impacts,  this is due to the variable seasonal solar radiation which maxes at the summer solstice ....

At the Arctic circle (latitude of southern Chukchi), insolation reaches 90% of its peak value around this time of year. Open water, clear skies... not good.

We can expect some rotation of ice from Beaufort into Chukchi, which would confound the regional impact of albedo forcing on a time scale of a melting season.

gerontocrat

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Re: Albedo-Warming Potential
« Reply #121 on: May 18, 2019, 05:08:54 PM »
A fella called Tealight, with the help of his Avatar Nico Sun, has done the biz at https://cryospherecomputing.tk/NRTawp. It is updated daily and is wunderbar. Note he has analyses for the Arctic in total, individual seas, and "The High Arctic" (=the seven seas of the Arctic Ocean itself)

Using his AWP data combined with lots of other maths re sea ice SST's etc, he has already smashed the opposition on forecasting Antarctic Sea Ice. I am hoping to see if he is going attempt the same for the Arctic.

Examples of graphs and maps attached.
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