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

Abstract

The nondimensional parameter space of an idealized dry primitive equation model is explored to find superrotating climate states. The model has no convective parameterization and is forced using a simple 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. The mode that drives the transition to superrotation in an intermediate-thermal-Rossby-number atmosphere is shown to behave like a Kelvin wave in the tropics. © 2014 American Meteorological Society.