Evaluation of ARAC`s participation in a long-range transport experiment

The 1994 European Tracer Experiment (ETEX) involved two releases of inert tracer gas in western France, allowing subsequent detection at many locations across Europe. Twenty four operational and research facilities from 20 countries made predictions of the motion of the released plume and the resulting concentrations detected at the sampler locations. This paper describes participation by the Lawrence Livermore National Laboratory`s Atmospheric Release Advisory Capability (ARAC) in ETEX. In its role as a real-time emergency response center, ARAC operates a suite of numerical models which simulate the advection and diffusion of airborne releases, and which calculate the estimated downwind concentration of the released material. The models and procedures used by ARAC to participate in ETEX were essentially the same as those which would be used to respond to a release at any previously unspecified location