I test different inversion parametrizations of vertical velocity and anisotropic parameter
. A model space parametrized by the squares of vertical and horizontal velocity results in vertical velocity and
updates with opposite signs. On the other hand, a model space parametrized by the logarithm of the vertical velocity squared and
has more reasonable updates, as well as better data matching. However, ambiguity does exist in the inversion results between vertical velocity and
. I clearly demonstrate these findings using a synthetic example.