Line Mixing in Water Vapor and Methane

A multispectrum fitting algorithm has been used to identify line mixing and determine mixing parameters for infrared transitions of H2O and CH4 in the 5–9 μm region. Line mixing parameters at room temperature were determined for two pairs of transitions in the v2 fundamental band of H216O, for self‐broadening and for broadening by H2, He, CO2, N2, O2 and air. Line mixing parameters have been determined from air‐broadened CH4 spectra, recorded at temperatures between 210 K and 314 K, in selected R‐branch manifolds of the v4 band. For both H2O and CH4, the inclusion of line mixing was seen to have a greater effect on the retrieved values of the line shifts than on the retrieved values of other parameters.