Published online by Cambridge University Press: 01 April 2008
In this paper we derive local error estimates for radial basis function interpolation on the unit sphere 
. More precisely, we consider radial basis function interpolation based on data on a (global or local) point set 
 for functions in the Sobolev space 
 with norm 
, where s>1. The zonal positive definite continuous kernel ϕ, which defines the radial basis function, is chosen such that its native space can be identified with 
. Under these assumptions we derive a local estimate for the uniform error on a spherical cap S(z;r): the radial basis function interpolant ΛXf of 
 satisfies 
, where h=hX,S(z;r) is the local mesh norm of the point set X with respect to the spherical cap S(z;r). Our proof is intrinsic to the sphere, and makes use of the Videnskii inequality. A numerical test illustrates the theoretical result.