A retrospective look at three 21st-century urban dispersion experiments: URBAN 2000, JU03 and MID05

Under the leadership of Jerry Allwine, three major urban dispersion experiments were conducted within a period of 6 years beginning in 2000 with URBAN 2000 and culminating in 2005 with MID05. URBAN 2000 was conducted in Salt Lake City, UT, while MID05 was conducted in Midtown Manhattan, New York, NY. Centered in the middle of these two experiments was JU03, known more completely as Joint Urban 2003, which was conducted in Oklahoma City, OK, in 2003. Each of these experiments added to our understanding of urban dispersion and each will be briefly reviewed in this presentation. Emphasis will be given to the experimental setup especially with regard to tracer sampling, terrain, and city morphology. Major results will be reviewed.

Salt Lake City was an urban area of few high buildings, but its setting was in a mountain basin adjacent to complex terrain that provided complex air flows. URBAN 2000 was conducted only at night. So called “upwind dispersion” occurred during this experiment.

Oklahoma City provided a compact business district with predictable mesoscale wind flows. Both nocturnal and daytime experiments were conducted. Over 20 government agencies and universities participated. JU03 was the most highly instrumented experiment of the three, with approximately 25 real-time tracer analyzers and 150 bag samplers. A dense deployment of sonic anemometers and other wind instruments helped to describe the urban and mesoscale wind flow. Nocturnal plumes had higher normalized concentrations but lower concentration fluctuations than daytime plumes.

Midtown Manhattan provided the most complex urban setting. Only daytime experiments were conducted, many under very light wind conditions. Much useful information has been gleaned from the data. Unfortunately this unique data set and the knowledge it has provided is not publicaly available and remains for official use only.