The Mock Urban Setting Test(MUST)was conducted for the Defense Threat Reduction Agency (DTRA) at the U.S. Army Dugway Proving Ground Horizontal Grid test site 6-27 September 2001. The experimental objective was to acquire meteorological and dispersion data sets at near full-scale for urban dispersion model development and validation. MUST collaborators included the U.S. Army Atmospheric Research Laboratory, the Canadian Defence Research Establishment Suffield, the UK Defence Science and Technology Laboratory, the U.S. Department of Energy Los Alamos National Laboratory, Arizona State University, and the University of Utah.

MUST was designed to overcome the scaling and measurement limitations of laboratory experiments and the characterization difficulties presented by real urban settings. It included a regular 12 by 10 array of conex shipping containers (each 12.2 m by 2.6m by 2.6m) that produced a wake interference flow regime and urban-scale roughness over a 200-m square area. Tracer gas (propylene) puffs or plumes were released from positions within or immediately upwind of the MUST array. Tracer dispersion through the array was measured using fast-response photoionization detectors (PIDs). A 32-m tower and several 6-m towers within the MUST array provided vertical sampling, while four sampling lines of PIDs provided lateral dispersion information. Sixty eight useable trial events, consisting of 63 continuous releases and 5 sets of puff releases, were completed during MUST, providing 16 hours of continuous release data and 4.75 hours of puff data for analysis. Analysis of the MUST data sets should provide useful insights into urban dispersion processes.