Incorporation of the thermal radiative effect of CH₄, N₂O, CF₂Cl₂, and CFCl₃ into the National Center for Atmospheric Research community climate model

This paper documents the incorporation of the radiative effect of trace gases CH 4 , N 2 O, CF 2 Cl 2 , and CFCl 3 into the National Center for Atmospheric Research community climate model (CCMl) longwave scheme, which presently includes the radiative effect of H 2 O, CO 2 , and O 3 . This development is intended for using the CCMl to study the combined greenhouse effect of increasing atmospheric CO 2 , CH 4 , CF 2 Cl 2 , CFCl 3 , and N 2 O. The radiative effect of the trace gases in a homogeneous layer is parameterized based on Wang and Shi's (1988) analytical expression for the total band absorptance. For an inhomogeneous path, a scaling approximation is used to calculate the effective total band model parameters. The same treatment of the overlapping gaseous absorption bands used in the present CCMl scheme is adopted for the new trace gases.