Dependence of radiative forcing calculations on infrared bandwidth

The SEA-ESF radiation algorithm employed in GFDL models has been modified to permit use of uniform narrow bands (as narrow as 1 cm-1) in the infrared frequency range. Spectral surface and top-of-atmosphere irradiances have been computed as a function of band width. The results are compared to values obtained using the operational GFDL radiation algorithm, to those from line-by-line calculations and to observed irradiance measurements. Radiative forcings for the historical and 21st century periods, with emissions and concentrations specified according to the RCP45 scenario are computed using the different SEA-ESF formulations.