Project 'Windbank' - Final Report

An emergency decision support system for accidental releases of radioactivity into the atmosphere providing regional wind field information was developed. This system is based on intensive meteorological field campaigns each lasting 4 months in the regions around the Swiss nuclear power plants. The wind data from temporary and permanent stations were analysed to evaluate the typical wind field patterns occurring in these regions. A cluster analysis for these data-sets lead to 19 different wind field classes with a high separation quality. In separate studies, it was demonstrated that an on-line acquisition of meteorological data from existing permanent stations is enough to diagnose the recent wind field class in a region with a diameter of about 50 km around the nuclear power stations with a probability of about 80% to hit the correct class. Furthermore, a method was developed to use a high resolution weather prediction model to forecast the future wind field classes. An average probability of over 60% to hit the correct class for a forecast time of 48 hours was evaluated. Finally, a method for parameterization of turbulence providing input for dispersion models from standard meteorological on-line data was developed. (author)