A ``stratified'' spectral model for stable and convective atmospheres (Q1335630)

Taking advantages of the simplicity of implementing implicit time stepping in spectral models, we solve a non-hydrostatic, fully compressible version of the hydrodynamic equations without the time step restrictions imposed by acoustic and gravity waves. To simplify the nonlinear terms and to conserve the total mass and total angular momentum to round-off accuracy, we introduce a ``stratified'' approximation which limits the nonlinearity of the equations to quadratic. The linear terms remain intact so that all the linear waves are preserved. Tests are presented to illustrate the capabilities and advantages of the present model.