Improvement of Worldwide Version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI), (I) New Combination of Models, Atmospheric Dynamic Model MM5 and Particle Random Walk Model GEARN-new

Abstract

The new version of WSPEEDI (Worldwide version of System for Prediction of Environmental Emergency Dose Information) is developed by introducing the combination of models, the atmospheric dynamic model MM5 and the Lagrangian particle dispersion model GEARN-new to improve the prediction capability of atmospheric dispersion of radionuclides discharged during nuclear emergency. The major improvements are (1) the forecasts of meteorological conditions with high resolution in time and space, (2) the simultaneous calculations for local and regional areas and (3) the consideration of detailed physical processes (e.g. wet deposition, vertical diffusion in atmospheric boundary layer). The performance of new models is evaluated by air sampling data on 137Cs over Europe during the Chernobyl accident. The calculated surface air concentrations showed good agreement with measurements.