  A simple variogram model with two parameters is presented that includes the
power variogram for the fractional Brownian motion, a modified De Wijsian
model, the generalized Cauchy model and the multiquadrics model. One parameter
controls the smoothness of the process. The other parameter allows for a smooth
parametrization between stationary and intrinsically stationary second order
processes in a Gaussian framework, or between mixing and non-ergodic max-stable
processes when modeling spatial extremes by a Brown-Resnick process.
