Validation of a mass consistent flow model as part of a decision support system

In the context of real time ton-line) decision support systems for nuclear installations, atmospheric dispersion and deposition has to be calculated f or a mesoscale area. Typically the wind field in this area is influenced by topography. Therefore, simple Gaussian type modelling is not appropriate. initiated and funded by the Bundesamt fur Strahlenschutz, simple (diagnosti c mass consistent) flow models were investigated which, with readily availa ble data, can realistically simulate the wind field in a large area. The ef fect of different initialization modes of the model has been evaluated. The flow model is one component of a model chain. Other important parts are mo dules to calculate the atmospheric dispersion, the radiation exposure and c ounter measures. The initialization of the flow model has been done based o n a) local meteorological observations, typical for a nuclear site, b) prog nostic data of the Deutschland-Modell (operational weather forecast model u p to the end of 1999) of the Deutscher Wetterdienst, and c) a combination o f both datasets a) and b). The present paper deals mainly with the performa nce of a mass consistent model initialized with the results of an operation al weather forecast model.