Error-growth dynamics and predictability of surface thermally induced atmospheric flow

Abstract Using the CSU Regional Atmospheric Modeling System (RAMS) in its nonhydrostatic and compressible configuration, over 200 two-dimensional simulations with Δx = 2 km and Δx = 100 m are performed to study in detail the initial adjustment process and the error-growth dynamics of surface thermally induced circulations including the sensitivity to initial conditions (i.e., the traditional predictability), boundary conditions, and model parameters, and to study the predictability as a function of the size of surface heat patches under a calm mean wind. It is found that the error growth (at least at the stage when the surface forcing is strong) is not sensitive to the characteristics of the initial perturbations. The numerical smoothing has a strong impact on the initial adjustment process and on the error-growth dynamics. The predictability is variable dependent. The mesoscale flow is insensitive to lateral and top boundary conditions. Among the conclusions regarding the influence of the boundary-layer ...