Abrupt transition to strong superrotation

The behavior of an axisymmetric shallow water model with an applied tropical torque was studied to determine if an abrupt transition can be realized without eddy feedbacks. For low values of the applied torque, the circulation was found to be Earth-like; however, for larger values, an abrupt transition to strong superrotation occurred. The bifurcation was caused by a positive feedback between the equatorial zonal wind and the strength of the Hadley cell.