Surface finite element approximation of spherical Whittle-Matérn Gaussian random fields

Preprint, 2021

Spherical Matérn-Whittle Gaussian random fields are considered as solutions to fractional elliptic stochastic partial differential equations on the sphere. Approximation is done with surface finite elements. While the non-fractional part of the operator is solved by a recursive scheme, a quadrature of the Dunford-Taylor integral representation is employed for the fractional part. Strong error analysis is performed, obtaining polynomial convergence in the white noise approximation, exponential convergence in the quadrature, and quadratic convergence in the mesh width of the discretization of the sphere. Numerical experiments for different choices of parameters confirm the theoretical findings.