A new parameterization of the absorptance due to the 15‐μm band system of carbon dioxide

A new parameterization for the absorptance due to the 15‐μm band system of CO 2 is presented. This parameterization is based on that described by Kiehl and Ramanathan (1983), but is more computationally efficient than the original parameterization. A Voigt line correction factor has been added to the parameterization to improve the accuracy of the model for stratospheric applications. Comparison of this band model with absorptances calculated from line‐by‐line results and a narrow band Malkmus model show good agreement for both homogeneous and inhomogeneous atmospheric cases. Radiative flux changes due to increases in CO 2 are also compared between the new broadband model, line‐by‐line model, and the narrow‐band model and are found to be in good agreement. The new broadband model is employed in the latest version of the NCAR Community Climate Model (CCM1).