Traditionally, chemical and biological (CB) defense systems analyses used to inform technology investment direction, system testing and evaluation, and ultimately system acquisition decisions have utilized an ensemble-averaged representation of the dispersion pattern. This is accomplished by using Gaussian puff and plume models that are derived from an ensemble of transport and dispersion realizations. More advanced Gaussian dispersion models like the Second Order Closure Integrated Puff (SCIPUFF) model are also capable of providing an estimation of variance of the dispersion about the mean, which is then used in these analyses. Recent advances in modeling of atmospheric dispersion have made it possible to now produce ensembles of “single-realization” dispersion scenarios at spatial scales and with time averaging periods significantly shorter than those used in the Gaussian puff and plume models. This single realization dispersion modeling capability allows for the creation of ensembles of transport and dispersion realizations that can be directly used in these analyses.

At NCAR, we developed a synthetic defense analysis system named the Virtual Threat Response Emulation and Analysis Testbed (VTHREAT). Unlike other defense analysis systems, VTHREAT utilizes the “single realization” dispersion scenarios instead of the ensemble mean representation. This presentation will show the impact of using a single realization system like VTHREAT in the analysis process, versus using an ensemble mean and variance representation of dispersion. It will also illustrate the enhanced information content that can be derived for these types of analyses that comes from computing the ensemble statistics at the end of the analysis versus the more traditional method of computing the ensemble statistics earlier in the analysis process. Specific examples, such as the use of VTHREAT for testing and evaluation of sensing technologies will be shown.