METRODOS: Meteorological preprocessor chain

Abstract The METRODOS meteorological preprocessor chain combines measured tower data and coarse grid numerical weather prediction (NWP) data with local scale flow models and similarity scaling to give high resolution approximations of the meteorological situation. Based on available wind velocity and direction measurements/ NWP predictions, the LINCOM or the MCF flow model determines the wind field on a 1 2 to 1 km grid over the area of interest, taking the influence of orography and mixed roughness into consideration. For each grid point the obtained wind and the most appropriate - normally the nearest - heat flux related measurement, e.g. a temperature gradient, are used to give local values of friction velocity and Monin-Obukhov length plus an estimate of the mixing height. The METRODOS meteorological preprocessor chain is an integral part of the RODOS - Real Time On Line Decision Support - program for nuclear emergencies, where the data fields generated by the preprocessor form the base for the calculation of dispersion and deposition of radioactive matter released to the atmosphere.