Supporting evidence for a positive water vapor/infrared radiative feedback on large scale SST perturbations from a recent parameterization of surface long wave irradiance

Summary In this note a recent parameterization of surface infrared irradiance as a function of screen temperature and precipitable water is studied. The primary purpose is to investigate whether this parameterization supports previous studies of the surface infrared radiation that show a positive water vapor/infrared radiative feedback on large scale surface temperature perturbations. The parameterization studied here, which uses screen temperature and precipitable water as input, has been shown previously to resemble observations very well compared with other simple parameterizations of the irradiance. The results of the present study, where precipitable water has been parameterized as a function of screen temperature, provide supporting evidence for a positive value of the water vapor/infrared radiative feedback. The estimated magnitude of the feedback lies within the range of previous studies.Revised April 2, 2002; accepted March 11, 2003Published online: August 7, 2003