tisdag 12 februari 2013

OLR Spectra Decoded as Fake!?

Consider the following outgoing long wave radiation OLR spectrum delivered by the Atmospheric Infrared Sounder AIRS flying on the Aqua satellite:

The graphs show the brightness temperature as function of wave number, with the brightness temperature the temperature of a blackbody with the same radiance at a given wave number as that recorded by the spectrometer (in principle bolometer) sensor, with in particular a zoom of the wave number interval 645 - 685 containing the main resonance at 667 of CO2.

We see a low brightness temperature of about 220 K and a peak at the main resonance at 667 of 250 K.  Both these brightness temperatures are lower than the temperature of 295 K in the atmospheric window between 800 and 1200, as if the sensor has recorded the presence of CO2 both at the tropopause (220 K) and in the middle of the troposphere (250 K).

We understand that a bolometer sensor measures radiance calibrated to blackbody radiance and thus cannot distinguish between low emissivity/high temperature and high emissivity/low temperature. This means that the assignment of brightness temperature is influenced by an unknown emissivity, which explains why the assigned brightness temperature is high at the main resonance 667 for which the emissivity is high, and low in the weak resonances surrounding the main resonance for which the emissivity is low. But it does not make sense that CO2 radiates from different temperatures for different frequencies, because all frequencies are assumed to have the same temperature.

The spectrum constructed is thus an artificial spectrum reflecting the sensitivity of the bolometer, which may be chosen so that resonances of CO2 are picked up before the continuous spectrum from the Earth surface, and then are assigned brightness temperatures according to radiance, as shown above. The weak resonances with low total emissivity of CO2 away from 667,  are then assigned a low brightness temperature (220 K) at full emissivity, as if all of the radiation from the Earth surface was blocked in the whole interval 600 - 800.

The OLR spectrum delivered by AIRS is thus an artificial spectrum constructed so as to hide that away from the main resonance 667, CO2 has small emissivity and thus cannot block all of the radiation from the Earth surface (even under doubled concentration from preindustrial level).

OLR spectra delivered by AIRS (and IRIS) are viewed as the key evidence of "heat trapping" or "radiation blocking" by atmospheric CO2. If these OLR spectra show to be fakes misrepresenting physics, the main scientific argument of CO2 alarmism evaporates.  So what does true science tell: fake or not fake?

PS To help discussion, recall the sparseness of the CO2 spectrum around 667 as pictured in the previous post.

1 kommentar:

  1. oh boy... i actually ended up here looking for the location a student of mine copied his homework from (no, nothing climate. just a parameter space conversion of electromagnetic spectra). and now i tear my hair...

    i get the strong feeling you should stay with maths and keep away from physics. at least from atmospheric physics and radiative transfer (or maybe you completely doubt that theory? chandrasekar having only done bullshit?).

    "as if the sensor has recorded the presence of CO2 both at the tropopause (220 K) and in the middle of the troposphere (250 K)."
    "cannot distinguish between low emissivity/high temperature and high emissivity/low temperature"

    first, you are aware that CO2 is a long-lived trace gas, so it's well mixed in the atmosphere and exists in the middle troposphere as well as around the tropopause. hey, man, even in the stratosphere and mesosphere. incredible, isn't it? (maybe some conspiracy?)

    second, ever got that emissivity is an "effective" parameter and does not make too much sense for understanding transparent media, particularly such that are not homogeneous, e.g. regarding temperature?

    the higher brightness temperature in the band center results from absorption getting so high, that transmission reaches close to zero already in the stratosphere (emissivity reaching 1!) and atmosphere radiates like a blackbody at the ambient temperature. which is - tataaa - higher than around the tropopause. obviously somewhat above 250K.
    a little further into the wings, transmission approaches zero somewhat lower in the atmosphere, where it is colder. so blackbody emission from ambient temperature produces lower intensities.
    wonders of the earth....

    ah, f***. i forgot einstein again. idiot i am.