Development of the new CCC/GCM longwave radiation model for extension into the middle atmosphere |
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| Authors: | VI Fomichev J‐P Blanchet |
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| Institution: | Department of Physics , University of Quebec at Montreal , Montreal, Quebec, H3C 3P8, Canada |
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| Abstract: | Abstract A new infrared (IR) radiation scheme for extending the CCC/GCM (Canadian Climate Center General Circulation Model) into the middle atmosphere is proposed. It combines the previous CCC/GCM radiation scheme including the effects of H2O, CO2, O3, CH4, N2O, CFC11 and CFC12, clouds and aerosols, with a new computationally efficient matrix parameterization for the cooling rate in the middle atmosphere for both LTE (local thermodynamic equilibrium) and non‐LTE layers. The matrix parameterization includes the effects of both the 15 μm CO2 and the 9.6 μm O3 bands and provides a proper lower boundary condition for the non‐LTE recurrence formula. The new scheme shows satisfactory agreement with line‐by‐line calculations. The absolute error does not exceed 0.8 ? day‐1 for vastly different atmospheric conditions. Introducing the new radiation module into the CCC/GCM results in deviations of the simulated temperature from the CIRA‐1986 model of not more than 10 ? throughout most of the altitude‐latitude domain. |
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