Power spectrum estimation of spherical random fields based on covariances

A Gaussian isotropic stochastic field on a 2D-sphere is characterized by either its covariance function or its angular spectrum. The object of this paper is the estimation of the spectrum in two steps. First we estimate the covariance function, secondly we approximate the series expansion of the covariance function with respect of Legendre polynomials. Simulations show that this method is fast and precise. Keywords: Angular correlation, angular spectrum, isotropic fields on sphere, estimation of correlatio