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A two‐dimensional mean circulation model for the atmosphere below 80km

1975; Wiley; Volume: 101; Issue: 430 Linguagem: Inglês

10.1002/qj.49710143003

1477-870X

R. S. Harwood, J. A. Pyle,

Atmospheric chemistry and aerosols

Abstract The paper sets out the detailed formulation of a numerical model whose purpose is the study of the interactions of dynamics, photochemistry and radiation in the stratosphere and mesosphere. Two integrations of the model for 900 days are described in which many features of the atmosphere are reproduced but with important differences of detail. The dependent variables are zonal means of the relevant meteorological quantities, held as functions of time, latitude and height (log pressure) with a resolution of μ/19 in latitude and 0.5 in pressure scale height. Eddy fluxes of heat and matter are treated by large‐scale diffusion coefficients. This treatment is not applicable to momentum fluxes: these are currently specified from observations made mainly from the selective chopper radiometer on the Nimbus V spacecraft. Radiative coolings due to CO 2 and O 3 emission are computed from simplified expressions which are essentially cooling‐to‐space approximations with emissivities obtained by curve‐fitting against the results of more elaborate treatments. Absorption of solar radiation by ozone is obtained from tabulations of absorption against ozone amount traversed. Radiation and latent heat release in the troposphere are specified climatologically. The photochemistry in the integrations described here is the classical ozone scheme but, with a view to investigating possible stratospheric pollution problems, integrations have been performed with the inclusion of reactions involving nitrogen and hydrogen compounds. These will be described in a later paper.