The refinement of a meteorological pre-processor for the urban environment

摘要

The meteorological pre-processor used routinely at the Finnish Meteorological Institute(FMI) has been modified in order better to represent urban conditions.We have reevaluated the roughness length,introduced the zero displacement height and divided the surface layer into a roughness sub-layer and an inertial sub-layer.The friction velocity and Monin-Obukhov length are evaluated using an empirically developed,exponential,Reynolds stress profile in the roughness sub-layer.The effect of these modifications has been studied by computing the dispersion parameters used in the urban dispersion modelling system UDM-FMI and comparing the revised parameters with the previous model computations.