Abstract: The mesoscale meteorological model WRF and the diffusion model FLEXPART-WRF are coupled to numerically simulate the diffusion process of the classic European long-distance tracer test (ETEX-1). At the same time, the meteorological and diffusion simulation results are compared with the meteorological observation and concentration monitoring data collected respectively during the ETEX-1 test, in combination with the tracer test data and the statistical verification method in MVK (Model Validation Kit). The results show that the average correlation coefficient between the simulated and observed meteorological wind components is 0.43, and the average root mean square error is 3.4 m/s. The particle diffusion trend is highly matched with the wind field, and the near ground transit concentration covers most monitoring stations. The statistical results of indicators also show that the simulation and monitoring results are in good consistency, and the simulation results can effectively reflect the current flow field and diffusion characteristics. The meteorological diffusion coupling model can be used to assist in evaluating the impact of airborne radioactive pollutant diffusion on the environment under nuclear accidents.

Key words: diffusion, coupling model, tracer test, numerical simulation