An evaluation of large-eddy numerical simulations of near-surface winds and chemical dispersion during the FFT-07 field program

The FUsing Sensor Information from Observing Networks (FUSION) Field Trial 2007 (FFT-07) field experiment was conducted at Dugway Proving Ground (DPG) in September, 2007. The purpose of this experiment was to provide a high spatial and temporal resolution chemical tracer and meteorological data set that could be used to improve the accuracy of Department of Defense (DoD) transport and dispersion (T&D) modeling capabilities. Comprehensive propylene gas tracer dispersion and meteorological conditions were collected using 120 fast-response chemical sensors deployed at a 50 m horizontal spatial resolution covering an area of ~500x500m. The experiment also involved the collection of detailed boundary layer meteorological observations both at the surface and aloft.

In this study we evaluate the EULerian semi-LAGrangian research model for geophysical flows (EULAG) and an imbedded passive tracer, transport and dispersion (T&D) model using both the chemical and meteorological observations from FFT-07. Physically realistic, atmospheric, and tracer gas release conditions are achieved by assimilating time-varying, composite, vertical profiles of wind and temperature based on the FFT07 observations. Ensembles of high-frequency (e.g. 1 Hz) model generated winds and gas tracer-gas concentrations were produced at the same locations as the individual meteorological and chemical sensors in FFT-07 experiment. The results illustrate the models ability to replicate both the mean and temporal fluctuations observed in the chemical dispersion and meteorological observations. Our findings suggest that this approach is suitable for simulating chemical and biological (CB) agent releases with sufficient fidelity for use in testing and evaluating CB defense systems.