Solar heating by the near‐IR CO₂ bands in the mesosphere

Absorption of solar energy by the near‐infrared (NIR) CO 2 bands provides an important source of heating in the mesosphere. At 60–85 km, this source exceeds 1 K day −1 and contributes up to 30% of the total solar heating. Calculation of the solar heating in the NIR CO 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 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 2 heating results in a significant warming of up to 8 K in the mesosphere for the current CO 2 amount but does not significantly change the model thermal response induced by the doubling of CO 2 .