Parameterizations for the Absorption of Solar Radiation by O₂and CO₂with Application to Climate Studies

Simple and accurate parameterizations have been developed for computing the absorption of solar radiation due to O2 and CO2. The parameterizations are based on the findings that temperature has a minimal effect on the absorption and that the one-parameter scaling can be applied to take into account the effect of pressure variation along a path. Furthermore, overlapping of the absorption due to CO2 and water vapor is treated accurately in the parameterizations. Simulations with a zonally averaged multilayer energy balance model show that the absorption of solar radiation due to O2 and CO2 has a small, albeit nonnegligible, effect on climate. The global surface solar radiation is reduced by 2.2 W m−2, and the warming of the surface temperature due to a doubled CO2 concentration is reduced by 10% in the Northern Hemisphere. Because the parameterizations can be easily implemented without perturbing other parts of a radiation routine, it is suggested that the absorption of solar radiation by O2 and CO2 be included in climate studies using numerical models.