Top plot: ratio of the surface density at two different azimuthal angles of of the disk from zonal flows simulation of Uribe et al. (2011). The azimuthal angles are chosen such that for a specific radius, the amplitude of the pressure bump has a maximum Σ_max, and a minimum Σ_min. Bottom plot: azimuthal velocity with respect to the Keplerian velocity for the azimuthal and time-averaged surface density of the midplane.