The abundance of CH<sub>4</sub> in the earth’s atmosphere was determined by assuming an effective temperature for the atmosphere of 250°K. The lines<i>R</i>(0) and <i>P</i>(2) of the 2<i>v</i><sub>3</sub> band were used since they are sensibly single and are easily broadened so that the total integrated intensity can be determined. The result of 1.11±0.16 cm.atm (NTP) is in good agreement with previously published results obtained by using less realistic effective temperatures.
UWE FINK, D. H. RANK, and AND T. A. WIGGINS, "Abundance of Methane in the Earth’s Atmosphere," J. Opt. Soc. Am. 54, 472-473 (1964)