SCIPUFF is used by the US Army to determine exposure levels of biological and chemical warfare agents. SCIPUFF (Second-order Closure Integrated Puff) model is a Lagrangian puff dispersion model developed by Titan's ARAP Group that uses a collection of Gaussian puffs to represent an arbitrary, three-dimensional time-dependent concentration. The turbulent diffusion parameterization is based on turbulence closure theory, providing a direct relationship between the predicted dispersion rate and turbulent velocity statistics of the wind field. In addition to the average concentration value, the closure model also provides a prediction of the statistical variance in the concentration field resulting from the random fluctuations in the wind field. The closure approach also provides a direct representation for the effect of averaging time. SCIPUFF has been incorporated into the Defense Threat Reduction Agency's (DTRA) Hazard Prediction and Assessment Capability (HPAC) software. HPAC is utilized for planning and analysis as well as in the field by military personnel to rapidly determine consequences of dispersing chemical, nuclear and biological agents. SCIPUFF has been validated against a number of laboratory and field experiments, demonstrating its usefulness for non-military applications. It has been recommended as an alternative model by the EPA which can be used on a case-by-case basis for regulatory applications. The publicly available version of SCIPUFF is the same version incorporated in HPAC except that the proprietary and developmental features have been disabled. SCIPUFF runs on a PC with a user-friendly Graphical User Interface (GUI).

The general features of SCIPUFF are as follows:

Continuous, instantaneous, moving and stack sources

Gaseous and particulate materials

Buoyant and non-buoyant releases

Flat and complex terrain

Dry deposition

Wet deposition and gravitational settling of particles

Linear decay of released materials

Short and long range transport

Fixed winds, surface or profile observations or gridded meteorological input accepted

Puff sampling capability (i.e., receptors)

In addition, SCIPUFF also:

Provides estimates of the uncertainty in the concentration field

Performs accurate treatment of wind shear

Merges puffs in addition to splitting them using an efficient adaptive multi-grid scheme

Uses an efficient adaptive time-stepping scheme

Utilizes static puffs near the source to reduce computation time.

Flexible output displays color contour plots of concentration and probabilities of exceeding user-specified concentrations.

* Description courtesy of Titan Systems Corporation