Intrinsic dynamics of the Eta regional model:: role of the domain size

This note investigates the dynamical properties of the Eta model, a state-of-the-art nested limited-area model, following the approach previously developed by the present authors. It is shown that the intrinsic dynamics of the model depends crucially on the size of the domain, with a non-chaotic behavior for small domains, supporting earlier findings on the absence of sensitivity to the initial conditions in these models. For such domains, the role of the boundary conditions is predominant in reproducing the natural variability of the atmosphere. For large domains, an intrinsic unstable dynamics is recovered that is only slightly modulated by the boundary conditions. The impact of these properties on the skill of the model is briefly discussed.