  In recent years the gas kinematics probed by molecular lines detected with
ALMA has opened a new window to study protoplanetary disks. High spatial and
spectral resolution observations have revealed the complexity of protoplanetary
disk structure and correctly interpreting these data allow us to gain a better
comprehension of the planet formation process. We investigate the impact of
thermal stratification on the azimuthal velocity of protoplanetary disks. High
resolution gas observations are showing velocity differences between CO
isotopologues, which cannot be adequately explained with vertically isothermal
models. The aim of this work is to determine whether a stratified model can
explain this discrepancy. We analytically solve the hydrostatic equilibrium for
a stratified disk and we derive the azimuthal velocity. We test the model with
SPH numerical simulations and then we use it to fit for star mass, disk mass
and scale radius of the sources in the MAPS sample. In particular, we use 12CO
and 13CO datacubes.
