Planetary and Space Science 5 pe

ised tat f pu to the atmospheres of both Venus and Saturn’s moon Titan. The main results are: (i) Venus ’ equatorial superrotation of 118m s results primarily from a balance between the momentum source of pumping by thermal tides and the momentum sink of meridional advection of wind shear by horizontal branches of the Hadley circulation; (ii) no solution is found for Titan’s stratospheric equatorial superrotation the maintenance of equatorial superrotation in the atmo-spheres of slowly rotating planets. Strong equatorial Most theories have described the possible mechanisms from one (above first four references) or two (above last three references) particular zonal momentum sources or the maintenance of the Venus equatorial superrotation are: (i) meridional momentum transport from mid-latitudes by superrotation in these models has been explained by horizontal eddy mixing that corresponds to an inverse cascade of energy from small-scale motions to large-scale ARTICLE IN PRESSones in two-dimensional (2D) turbulence. Such an inverse cascade that transports the angular momentum equator-ward by barotropic waves can also be simulated an