Abstract
A semi-Lagrangian and alternating direction implicit method for integrating a multilevel primitive equation model is presented. The method derives from an earlier scheme developed by Bates for integrating the shallow water equations, though splitting is not used in the present case.
A linear analysis assuming an isothermal basic state shows that the scheme is unconditionally stable for advection and has the same lenient stability criterion for gravity-inertia waves as in the shallow water case.
Integrations are carried out using real atmospheric data and the model’s performance is compared with that of an explicit semi-Lagrangian model and of a semi-implicit semi-Lagrangian model.
