the rapid radiative transfer model (rrtm) is a validated, correlated k-distribution band model for the calculation of solar and thermal-infrared atmospheric radiative fluxes and heating rates. the rapid radiative transfer model for gcms (rrtm-g) is an accelerated version of rrtm that provides improved efficiency with minimal loss of accuracy for application to general circulation models. the latter divides the solar spectrum into 14 bands within which a total of 112 pseudo-monochromatic calculations are performed, and in the thermal infrared 16 bands are used within which 140 pseudo-monochromatic calculations are performed. rrtm-g is used in a number of general circulation models worldwide, such as that of the european centre for medium-range weather forecasts.