Dynamics, statistics and predictability of fine-scale and coarse-grained fields in a variable resolution system: a case study

A coupled map lattice system giving rise to spatio-temporal chaos is used to test the statistical performance of variable mesh models (VMMs), whereby a limited-area domain incorporating the highest temporal and spatial resolutions of the fields available is coupled to an outer domain descriptive solely of the gross, coarse-grained, features of the dynamics. The validity of this scenario, routinely used in regional weather forecasts, is investigated. It is found that the success of the description depends crucially on the existence of a scale separation in the dynamics and on the size of the limited-area domain. A detailed analysis of the instability patterns in space using an optimal choice of the parameters fulfilling these requirements shows that such models may prove valuable in carrying out probabilistic predictions of fields generating complex spatio-temporal behavior.