Schematic diagram of radiation scheme

       (Click to see how the equations are calcuated in codes!)


    Brief Introduction to radiation scheme

 "The object of any parameterization of atmospheric radiation for use in an atmospheric circulation model is to provide a simple, accuate and fast method of calculating the total radiative flux profile within the atmosphere" -  Stephens (1984)

 The radiation scheme implemented in CESAGCM is based on Nakajima and Tanaka (1986). This scheme uses discrete-ordinate method and k-distribution method for the calculation of optical thickness of gases. Total radiative band is divided by 18 bands and the upward/downward radiative fluxes (both for the longwave and shortwave) at each model layer is calculated at each band. Calculations are separately conducted for longwave and shortwave components. To determine the radiative fluxes using 2 stream approximation, the radiative properties  (emission and absorption/scattering coefficients) are calculated in advance. In that part, absorption by gases (H2O, CO2, O3, N2O, CH4), continua(H2O, O2, O3) and CFCs are considered. And the amount of cloud water/ice and aerosol are used for the scattering.