Spherical‐spline parameterization of three‐dimensional earth models

We propose a spherical surface‐spline method that parameterizes a two‐dimensional model on a sphere in terms of a local cubic B‐spline basis on a triangular grid of knots with approximately equal interknot spacing. Numerical results show that such a parameterization can represent a model on a sphere with an accuracy equal to that of the spherical‐harmonic parameterization of the corresponding nominal degree. Furthermore, it significantly reduces the computational time needed to calculate surface‐wave synthetic seismograms on a laterally heterogeneous Earth, and makes it feasible to apply JWKB theory to surface‐wave inversion studies.