Solar heating by the near-IR CO sub(2) bands in the mesosphere

Absorption of solar energy by the near-infrared (NIR) CO sub(2) bands provides an important source of heating in the mesosphere. At 60-85 km, this source exceeds 1 K day super(-1) and contributes up to 30% of the total solar heating. Calculation of the solar heating in the NIR CO sub(2) bands requires consideration of complex non-local thermodynamic equilibrium (non-LTE) processes. The small energy effect, narrow region of importance, and the necessity to consider non- LTE effects, have accounted for the absence of an adequate parameterization for the NIR CO sub(2) bands. Recently a parameterization has been developed and implemented into the Canadian Middle Atmosphere Model. Numerical experiments with this model have shown that inclusion of the NIR CO sub(2) heating results in a significant warming of up to 8 K in the mesosphere for the current CO sub(2) amount but does not significantly change the model thermal response induced by the doubling of CO sub(2).