In a previous article, I attempted to figure out a more accurate surface temperature for an imaginary Earth with no atmosphere compared to the standard approach of completely neglecting surface emissivity. The formula I used is:
The result I got was 273.6 K. This gives me a theoretical greenhouse gas warming of about 16.1 K, or about half using the standard approach.
The problem with this result is that I used a globally averaged albedo and emissivity.
A more accurate way to do this is to break the up the Earth into small pieces and calculate local temperatures based on local insolation, local albedo, and local emissivity. Then average that.
The only project that I’ve managed to find that provides broadband emissivity data is NASA’s ISCCP. It’s a bit dated: 1983 to 2004, but why not use it?
The Earth is broken down into 6596 equal area pieces:
The needed calculation can be summarized:
The result I got is:
$ . isccp.sh ; short | avg
268.82074This is ~ -4.3°C.
For fair assessment, we also need to do the same type of operation on ISCCP’s upwelling longwave radiation:
$ . isccp.sh ; long | avg
287.34596The difference is ~ 18.5 K.
Now let’s take a look at common propaganda taught to children:
Nope. The correct answer is -4.3°C !
Enjoy 🙂 -Zoe
Code
# Zoe Phin, 2022/07/01
# File: isccp.sh
# Run: . isccp.sh ; download ; short | avg ; long | avg
grab() { wget -qO- $1 | od -An -tf4 -v -w4 --endian=big; }
download() {
grab "https://isccp.giss.nasa.gov/pub/data/surface/D1AVGANN__BBEMIS" > em.is
grab "https://isccp.giss.nasa.gov/pub/data/FC/FDAVGSON__SWXXTOADW" > sw.in
grab "https://isccp.giss.nasa.gov/pub/data/FC/FDAVGANN__SWFLSRFDW" > sw.dn
grab "https://isccp.giss.nasa.gov/pub/data/FC/FDAVGANN__SWFLSRFUW" > sw.up
grab "https://isccp.giss.nasa.gov/pub/data/FC/FDAVGSON__LWFLSRFUW" > lw.up
}
avg() { awk '{S+=$1;N+=1}END{printf "%.5f\n",S/N}'; }
short() {
paste sw.in sw.dn sw.up em.is lw.up | awk '!/*/{
printf "%.5f\n", ($1*(1-$3/$2)/$4/5.670367E-8)^0.25
}'
}
long() { awk '{ printf "%.5f\n", ($1/5.670367E-8)^0.25}' lw.up; }
Zoe's Insights 
Damn, Zoe – Impressive as alway :-0 The stuff you do is so simple, straightforward and clearly presented, you’re one of the very few people I *immediately* check out posts from as soon as I see the notification in my email.
Why isn’t there anyone else doing these kind of first-principles sanity-check calculations? I accept that you’re pretty special, but cr*p, there’s gotta be more than one Zoe out of 8 billion humans on the planet
😉
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🤗
Very Nice! Thank you!
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Great article ! Davee54 said it all ! I am wondering what professional climatologists have to say in this regard. Too bad for them, they look so dumb in the light of your articles.
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Thank you 😀
They will say that since the difference between surface upwelling and OLR implies 33C, that’s the greenhouse effect … but then still claim that without an atmosphere it would ~18C, because you know, that’s just the convention. Yeah, it’s misleading … but we put it in all the textbooks, so deal with it.
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interesting Zoe – using the ‘ole UCAR archived site link to their kids-level ‘Earth Energy Balance’ calc, using the 12% moon albedo average, gives us a surface temp of -4C
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Thanks, Zoe. Your calculations are interesting, but they leave out a LOT of unknowns.
Here’s a discussion of some of the issues.
Earth’s baseline black-body model – “a damn hard problem”
w.
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Looks like the link no workie. Here it is again.
w.
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For the purpose of demonstrating the existence of the greenhouse gas effect, it’s not all that hard. For example, see Arthur Smith’s explanation: https://arxiv.org/abs/0802.4324
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That’s what I’m talking about: The dualistic nature of the greenhouse effect explanation. In my post I find the temperature of Earth without an atmosphere then compare that to actual temperature (18.5K)
In his, he finds the difference between surface and mean atmosphere (33K). That’s fine if you want to do that. You can attach a name to anything you want … but then don’t tell us the Earth would be 33K colder without atmospheric GHGs.
Also, he models a sphere. I use oblate spheroid data.
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In your code, why are SWFLSRFDW > sw.up, and SWFLSRFUW > sw.dn, when apparently to the contrary LWFLSRFUW > lw.up?
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Good point. In the code I find albedo by sw.dn/sw.up, which gives me the right answer because it’s really UW/DN.
So essentially … I double swapped the labels and got the correct answer.
I’ll fix the labels. Thank you for pointing it out.
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Emissivity really can be treated as 1 for practical purposes. No need to go to all this trouble. Also, the emmisivities you are using are not at all direct measurements. They are output by models with substantial assumptions and uncertainties. See https://scienceofdoom.com/2013/02/17/visualizing-atmospheric-radiation-part-thirteen-surface-emissivity/
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lol. Do you have a brain?
Your source:
“The oceans, covering over 70% of the earth’s surface, have an emissivity of about 0.96. Other areas have varying emissivity, going down to about 0.7 for deserts.”
“Emissivity really can be treated as 1 for practical purposes.”
What practical purpose would there be to live in fantasy land? Psychological feel-goodery? Enjoy being there.
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Hmmmm, no atmosphere temp here claims -46C.
https://www.academia.edu/resource/work/1891389
Albedo choices??
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