Measurements, made in different laboratories, of absorption by water vapor in microwave windows are compared with models for the water vapor continuum. A reanalysis of some of these measurements leads to the conclusion that the laboratory data are best represented by a combination of Liebe's [1987] millimeter-wave propagation model (MPM) for the foreign-broadened component of the water continuum and the 1993 version of MPM for the self-broadened component. This combined model is validated by comparison with measurements of atmospheric microwave emission.
Radio Science carries original scientific contributions on all aspects of electromagnetic phenomena related to physical problems. These contributions can include propagation through and interaction of electromagnetic waves with geophysical media, biological media, plasmas, and man-made structures. Coverage includes, but is not limited to, the application of electromagnetic techniques to remote sensing of the Earth and its environment, telecommunications, signals and systems, the ionosphere, and radio astronomy. All frequencies (including optical) are considered.
Absolute absorption rates of pure water vapor and mixtures of water vapor and nitrogen have been measured in the atmospheric window at 239 GHz. The dependence on pressure as well as temperature has been obtained. The experimental data are compared with several theoretical or empirical models, and satisfactory agreement is obtained with the models involving a continuum; in the case of pure water vapor, the continuum contribution based upon recent theoretical developments gives good results. The temperature dependence is stronger than that proposed in a commonly used atmospheric transmission model.
