A dynamic and thermodynamic foundation for modeling the moist atmosphere with classical thermodynamics and parameterized microphysics

In the design of our model of moist atmosphere, cloud-scale convection is explicit but microphysical processes of precipitation are parameterized. While the foundation of all the prognostic models should be the conservation principles of mass, momentum and energy, it has been customary to allow various approximations that are deemed meteorologically justifiable. It was shown by Ooyama (1990) that it would be simple to formulate reversible moist processes without those approximations but rather in terms of classical thermodynamics. Since then, the theory has been extended to include parameterized irreversible processes, accounting for the mass and entropy of precipitating water. As a further addition to this theory, the present paper discusses a consistent formulation of dynamic equations that correctly account for the momentum of precipitating water.

The theory has been successfully tested by our nested spectral model. Some results of interest will be demonstrated.