Toward understanding the sensitivity of the QUIC dispersion modeling system to real input data

QUIC (Quick Urban and Industrial Complex) is a fast response urban wind and particle dispersion modeling system. QUIC can be used in real-time or in training scenarios such as evacuation and clean up as a result of intentional or accidental chemical or biological releases. QUIC consists of a wind model (QUIC-URB), a particle dispersion model (QUIC-PLUME) and graphic user interface (GUI-GUI). QUIC-URB computes a 3-dimensional flow field in an urban area by enforcing mass conservation on an empirically based wind field. QUIC-PLUME is a Lagrangian dispersion model that solves the Langevin random walk equations. The objective of this study is to validate QUIC using data obtained from the JU2003 (Joint Urban 2003) field experiment conducted in Oklahoma City. This experiment consisted of tracer gas releases from varying locations in the CBD (central building district) of Oklahoma City with a dense array of samplers located in the downtown area as well as downstream of the CBD at varying distances up to 4km. To validate the QUIC model a methodology was developed that can be generalized for any dispersion model. Model evaluation in real urban environments involves utilizing field measurements to construct an appropriate inflow boundary conditions that allow for the most reasonable evaluation of the model. It is also important to understand the errors associated with field measurements and account for them appropriately. The work presented here describes the procedure involved in selecting an appropriate boundary condition as well as using experimental uncertainty in field measurement locations to most appropriately evaluate the model. The sensitivity of the QUIC generated solution to the specified inflow wind profile is discussed. This analysis shows quantitative paired in time and space comparisons of measured quantities (wind speed and direction, concentrations and turbulent kinetic energy) between the QUIC solutions and the JU2003 data using appropriate error metrics to quantify the overall performance of the dispersion modeling system. To benchmark the performance of QUIC against an existing standard, the model was compared to a standard urbanized Gaussian plume model.