Evaluation of the QUIC Urban Dispersion Model using the Salt Lake City URBAN 2000 Tracer Experiment Data – IOP 10

This work compares simulations produced by the Quick Urban and Industrial Complex (QUIC) dispersion modeling system to the Salt Lake City URBAN 2000 field experiment tracer measurements from two of the intensive operating periods (IOP's 9 and 10). QUIC is a fast response model that can approximate the 3D wind fields and plume concentration fields around building complexes. The URBAN 2000 field experiment where conducted in October 2000 by the US Department of Energy's Chemical and Biological National Security Program (CBNP) (Allwine et al., 2002) and it focused on transport and dispersion over building, multi-block and city scales. In this paper the QUIC-computed concentration fields were compared with the field experiment tracer measurements. During each of the three trials within each IOP, the wind direction usually varied significantly over the course of the experiment, such that a time-varying inflow wind profile was constructed using ten minute averaged velocity data. In the presentation, we will discuss the differences between the measurements and model-computed concentration fields. We will show how the concentration field produced using the time-varying inflow wind profile improved the point-by-point comparison of concentrations significantly as compared to using a one hour average wind profile. Finally, we will explain what we consider to be the root causes of the model-measurement differences, including the ambiguity in specifying the inflow wind profile, uncertainties in how to parameterize turbulence, inaccuracies in the computed mean flow fields, and approximations in defining the domain (e.g., no trees and no parking garages in the QUIC simulations).