On stochastic perturbation of simple blocking models.

Discusses some problems connected with the stochastic dynamics generated by the effect of small random perturbations acting on prototype equations governing large-scale flows. We focus on the features of the process which occur when the main instability is the result of orographic forcing on simple barotropic motion. In particular, we study a three-mode truncation of barotropic flow over topography when a stochastic white forcing acts on the system.