Models Methods Software

Dan Hughes

Equilibrium, Energy Balances and Budgets, and Stuff

Recently I ran across the following comments on a blog. The comments are followed by my response.

1.

“The physics of the direct warming effects of increased concentrations of CO2 and other infrared-absorbing gasses is completely clear.”

Let me try, “The physics of radiative-energy transport phenomena and processes given changing compositions of CO2 and other infrared-absorbing gasses in a homogeneous mixture of gases is completely clear.”

In fact, I think this can be expanded to include all radiative-energy transport phenomena and processes, ( absorption, transmission, and reflectance ), for both ultra-violet and infrared radiation, so long as homogeneous mixtures of gases are the material.

For me, one question is, How does this relate to the Earth’s atmosphere, oceans, ice, and land, and all the materials in and on these, and all the phenomena and processes occurring within and between these?

2.

“So, yes, one must combine this measurement of anthropogenic CO2 with the simple radiative physics in the atmosphere to get the fact that we expect AGW.”

The radiative-energy transport phenomena and processes occurring in the Earth’s atmosphere are far from ‘simple’. If these were simple, I think the treatment of them in mathematical models could be fairly characterized as being based on the full and complete fundamental equations associated with these, depend solely on properties of the materials of interest free of any parameterizations, accurate numerical solution methods known and fully incorporated into all GCMs, and resolution of all temporal and spatial scales accurately resolved for every calculation.

So far as I am aware, none of these conditions are met. The parameterizations for some of the phenomena and processes associated with radiative-energy transport in the Earth’s atmosphere are in fact used to tune the GCMs when improvements in hindcasts are needed. The properties of materials as they appear in the fundamental equations for any phenomenon or process are never used as tuning knobs.

I’ll add now, that R. D. Cess, V. Ramanathan, G. E. Thomas, K. Stamnes and a few other people might be surprised to learn of the simplicity of radiative-energy transport calculations in the Earth’s atmosphere. The earth’s atmosphere is not a homogeneous mixture of gases; it’s far more complex. Some of the materials that make the Earth’s atmosphere a heterogeneous mixture of gases, vapor, liquid, and solids have critically important interactions with the radiative energy transport.

Recently, I also ran across this statement in an online kind-of textbook:

“To develop this understanding we must discuss various forms of energetic equilibria in which a physical system may reside. Earth (and the other terrestrial planets, Mercury, Venus, and Mars) are said to be in planetary radiative equilibrium because, on an annual timescale the solar energy absorbed by the Earth system balances the thermal energy emitted to space by Earth.”

My bold.

The writer has specified a time scale over which the in-come and out-go of radiative energy for the Earth’s systems are balanced; ‘annually’. In my opinion there is no foundation whatsoever for this statement. By the same token, I think that this is the first time that I’ve seen any temporal scale attached to the radiative-equilibrium hypothesis. This one is clearly unsupported, however. The Earth’s systems both receive and reject energy on all temporal and spatial scales. Yes, the Earth’s systems, at this very instance, are losing energy to deep space and this seems to be frequently overlooked.

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March 10, 2010 Posted by | Uncategorized | , , | 3 Comments