Wave diagnosis for superrotating zonal flows

The existence of a fast zonal jet at the equatorial region in slower-rotating bodies as Venus and Titan's is a characteristic of superrotating atmospheres. Such a structure of winds implies in eddy momentum convergence at the tropics in order to balance the divergence of momentum by the mean meridional circulation. The Gierasch-Rossow-Williams (GRW) mechanism establishes that the barotropically-unstable jets in high latitudes induce perturbations which would carry momentum upgradient and then feeding the flow in the tropical region. However, this idea present in the GRW mechanism on propagating extratropical modes would lead to deceleration of the flow in the equatorial regions and, therefore, these waves cannot be the cause of equatorial superrotation. This study analyzes the main patterns and dynamical characteristics of the wave-like response in superrotating flows in higher-number-atmospheres. For that we performed simulations with the version 3.3.1 of the Weather Researcher and Forecast model, in which the diabatic and frictional effects were given by a Newtonian cooling and Rayleigh friction. Our results show that superrotation requires a specific pattern of waves. Rather than these extratropical modes, tropical waves are likely to be responsible of the maintenance of the strong zonal flow.