abstract This letter considers stationary local approximations to intrinsically stationary random functions on . For any continuous variogram [gamma] and any ball in , there exists a covariance function with compact support whose respective variogram is arbitrarily close to [gamma] when...

We derive sufficient conditions for the cross-correlation coefficient of a multivariate spatial process to vary with location when the spatial model is augmented with nugget effects. The derived class is valid for any choice of covariance functions, and yields substantial flexibility between...

We derive a class of matrix valued covariance functions where the direct and cross-covariance functions are Matérn. The parameters of the Matérn class are allowed to vary with location, yielding local variances, local ranges, local geometric anisotropies and local smoothnesses. We discuss...

type="main" xml:id="rssc12064-abs-0001" <title type="main">Summary</title> <p>The Lyon–Fedder–Mobarry global magnetosphere–ionosphere coupled model LFM-MIX is used to study Sun–Earth interactions by simulating geomagnetic storms. This work focuses on relating the multifidelity output from LFM-MIX to field...</p>

The extremal coefficient function has been discussed as an analog of the autocovariance function for extreme values. However, as to the behavior of valid extremal coefficient functions little is known apart from their positive definite type. In particular, the reconstruction of valid processes...