Spontaneous superrotation and the role of Kelvin waves in an idealized dry GCM

The nondimensional parameter space of an idealized dry primitive equations model is explored to find superrotating climate states. The model has no convective parameterization and is forced using a simple zonally symmetric thermal relaxation to a prescribed radiative equilibrium temperature. It is demonstrated that of four nondimensional parameters that determine the model's state only the thermal Rossby number has a significant effect on superrotation. Evidence suggests that the mode driving the transition to superrotation in an intermediate thermal Rossby number atmosphere is a Kelvin wave modified by meridional shear.