Simulation of the Chernobyl dispersion with a 3-D hemispheric tracer model

A 3-dimensional (3-D) hemispheric tracer model is employed for the long-term simulation of the dispersion of the nuclear debris from the Chernobyl accident. The most important features of the model are a fully three-dimensional advection-diffusion equation and a simple diagnostic parameterization of the boundary-layer mixing, dry deposition and wet scavenging. The tracer model is driven by a series of meteorological fields derived from the hemispheric objective analysis scheme of the Canadian Meteorological Center (CMC). The accident scenario employed in the simulation was derived from the data presented at the post-accident meeting of the International Atomic Energy Agency (IAEA) in Vienna in August 1986. Verification of the model indicates good accuracy and substantial improvement compared to the preliminary experiments with a very simple 2-dimensional (2-D) hemispheric tracer model.