Deviation Δ of the orbital velocity of a gas element with respect to an object orbiting with the full Keplerian frequency, normalised by the local sound speed, is plotted as function of orbital radius r in AU. The bold black line represents the traditional MMSN scaling, while the bold red line corresponds to the adapted MMSN as presented in Chiang & Youdin (2010). The shaded area connecting to thin curves indicates the effect of a strong pressure bump of strength δΔ =  −0.04. The adopted standard value of Δ = 0.05 in this paper, is accurate in a region around 5 AU, even without a strong pressure bump.