Half-widths and Line Shifts of Water Vapor for Atmospheric Applications: Measurement and Theory Short Title: Half-widths and Line Shifts of H O

Pressure-broadened half-widths are the principal source of error in the retrieval of concentration profiles for the Earth’s atmosphere. The importance of the pressure-induced line shift is now becoming understood. In this work the current state of knowledge of the line shape parameters for water vapor transitions is discussed with respect to the experimental record and the theory. The measurement databases that have been compiled and the intercomparisons of measurements are discussed. The theoretical determination of the line shape parameters via the Complex Robert-Bonamy (CRB) formalism is presented. The dependence of the line shape parameters on rotational state, vibrational state, imaginary terms, temperature, intermolecular potential, collision dynamics, and method of calculation are discussed. Finally a comparison of the CRB line shape parameters with the measurement database is made and compared with the intercomparisons of the measurements.