By plotting the strength of the B - mode signal as a function of frequency, the scientists could have determined whether the curve resembled the shallow rise of the cosmic microwave background or the steeper rise of dust light. (quantamagazine.org)
While the emission is a function of frequency and height, the general average for CO2 is usually assumed to come from a region with -53 deg. (realclimate.org)
As a function of frequency ν, log (τ) ~ = τpeak — M1 * (νpeak - ν) for ν νpeak. (realclimate.org)