Effective Radiative Level

There is this concept that by averaging all the different radiative spectra that satellites see from earth from very high altitudes an Effective Radiative Level can be derived that has meaning for the radiation balance for the planet.

The basic idea is that the addition of greenhouse gasses, predominantly CO2 by humans, will raise the Effective Radiative Level. The further idea is that this supposed increase in altitude for the radiative level takes place within the part of the atmosphere where there is lapse, i.e. the atmosphere cools with increasing altitude.

The claim is that since a higher altitude implies a cooler temperature, the radiation to space will take place at a lower blackbody temperature with lower energy to the fourth power, and will cool the planet less effectively.

We have developed the tools to evaluate this claim. Rather than a single average level and blackbody temperature, the satellites see substantial differences in radiative altitude across the earth longwave spectrum.

All Down Looking, Planck Bounding

The “effective” radiation seen from space in the earth long wave spectrum ranges about 100K, from a remarkably consistent  220+-7K for the CO2 bands to a wildly different 320K+ in the atmospheric window.

The bottom line is that CO2 has its own radiative channel to space entirely separate from the effective Planck temperature of the atmosphere as a whole. This channel radiates at the tropopause and above where the lapse rate reverses and becomes negative. Rather than radiating at a lower temperature, with increasing concentration and higher radiative altitude, CO2 radiates to space to the fourth power of a higher temperature with increasing concentration.


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