The N 2-broadened water vapor absorption line shape and infrared continuum absorption—II. Implementation of the line shape

Abstract

The total line shape model of the previous paper is tested using a set of experimental room temperature H 2O continuum measurements of high quality. Parameters of the far wing component of the total line shape are determined from near band experimental data. Grating spectrometer measurements from 300 to 650 cm −1 are used to determine unknown far wing parameters of the pure rotational band of H 2O. CO and HF laser measurements taken in the 5 and 3 μm regions are used to determine the far wing parameters of the ν 2 and ν 1, ν 3 fundamental bands, respectively. The total line shape model is applied to the 10 and 4 μm transmission windows with encouraging success. A significant increase in the self-broadening ability of H 2O over N 2 is predicted in the far wing. This procedure allows the proper modeling of the absorption coefficient vs H 2O partial pressure dependence in all window regions. A negative temperature is predicted by the model in the continuum. The observed rate of the temperature decrease is not predicted by the model; however, this limitation is related to the approximations made on the interaction potentials and the perturbation expansion of the Hamiltonians. Although the total line shape has limitations, it does demonstrate the importance of considering far wings of absorption lines in continuum absorption.