WATER-VAPOR ABSORPTION IN THE ATMOSPHERIC WINDOW AT 239 GHZ

Absolute absorption rates of pure water vapor and mixtures of water va por and nitrogen have been measured in the atmospheric window at 239 G Hz. The dependence on pressure as well as temperature has been obtaine d. The experimental data are compared with several theoretical or empi rical models, and satisfactory agreement is obtained with the models i nvolving a continuum; in the case of pure water vapor, the continuum c ontribution based upon recent theoretical developments gives good resu lts. The temperature dependence is stronger than that proposed in a co mmonly used atmospheric transmission model.