The vertical extension of a general circulation model generally requir
es a modification of the model's highly parameterized radiation scheme
in order to include approximately the absorption by lines with a Voig
t profile. For the European Centre for Medium-Range Weather Forecasts
radiation scheme, a modification of the Lorentz line width provides a
practical solution for this problem. Thus, the domain of this wideband
radiation scheme is extended from the surface up to the mesopause.