  We consider a multilayer generalization of Ripa's inhomogeneous-density
single-layer primitive-equation model. In addition to vary arbitrarily in
horizontal position and time, the horizontal velocity and buoyancy fields are
allowed to vary linearly with depth within each layer of the model. Preliminary
results on linear waves and baroclinic instability suggest that a configuration
involving a few layers may set the basis for a quite accurate and numerically
efficient ocean model.
