Line shape parameters of the 22-GHz water line for accurate modeling in atmospheric applications

Highlights: • Line shape parameters of one of the major atmospheric diagnostic lines are refined. • Two high resolution microwave spectrometers with complementary abilities were used. • The speed dependence effect on the line shape was evaluated for the first time. The paper concerns refining parameters of one of the major atmospheric diagnostic lines of water vapor at 22 GHz. Two high resolution microwave spectrometers based on different principles of operation covering together the pressure range from a few milliTorr up to a few Torr were used. Special efforts were made to minimize possible sources of systematic measurement errors. Satisfactory self-consistency of the obtained data was achieved ensuring reliability of the obtained parameters. Collisional broadening and shifting parameters of the line in pure water vapor and in its mixture with air were determined at room temperature. Comparative analysis of the obtained parameters with previous data is given. The speed dependence effect impact on the line shape was evaluated.