Main role of the horizontal diffusion schemes in numerical models nowadays is to remove the information without forecast value and the energy accumulated due to finite truncation of a model
spectrum acting as a numerical filter. However, during intensive cyclogenesis, especially over steep surfaces, the physical horizontal diffusion should not be neglected. A stable and efficient non-linear
horizontal diffusion, based on the control of the degree of interpolation needed for the Semi-Lagrangian advection scheme, has been implemented in ALADIN. The results of several numerical experiments show better simulation of a mesoscale Adriatic cyclones, upper troposphere cyclones and beneficial impact on forecast of low cloudiness in anticyclones
