| Joint urban 2003 (JU03) SF₆ atmospheric tracer field tests - :12573 | Office of Oceanic and Atmospheric Research (OAR)
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Joint urban 2003 (JU03) SF₆ atmospheric tracer field tests
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Joint urban 2003 (JU03) SF₆ atmospheric tracer field tests
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  • Description:
    This report summarizes the release, measurement, and analysis of the nontoxic, invisible, inert atmospheric tracer sulfur hexafluoride (SF6) and meteorological measurements by the Air Resources Laboratory Field Research Division (ARLFRD) during the Joint Urban 2003 (JU03) Experiment. The experiment's purpose was to study atmospheric dispersion in an urban environment. JU03 was conducted during July 2003 in Oklahoma City, Oklahoma. SF6 was released as a tracer during ten Intensive Observation Periods (IOPs). Each IOP included two or three quasi-continuous (30-min.) point releases, and three to six instantaneous puff releases. The 10 IOPs produced data for a total of 29 continuous releases (17 daytime, 12 nocturnal) and 40 puff releases (25 daytime and 15 nocturnal). SF6 concentrations were sampled and measured as the tracer dispersed through Oklahoma City. Sampling was done using programmable integrating gas samplers (PIGS) and new Super PIGS, and quasi-instantaneous measurements were taken using fast-response trace gas analyzers (TGAs). The samplers were positioned at approximately 150 locations within Oklahoma City, which included street level, rooftop, and pedestrian tunnel locations within the central business district (CBD), and on arcs at distances of 1, 2, and 4 km from the point of tracer release. Quality control samplers were also positioned at selected stationary sampler locations. Ten van-mounted TGAs were also driven to varying locations within Oklahoma City to intercept dispersing tracer plumes. ARLFRD deployed meteorological equipment at the release site and on the Oklahoma School of Science and Mathematics campus in support of the JU03 project. This report contains ARLFRD release and tracer data summaries for each IOP, descriptions of tracer sampling equipment, information on how the data were obtained and processed, and the associated quality control procedures. Analysis of the sampler data leads to the following conclusions: (1) concentrations measured at street level often exceeded rooftop-level measurements by a factor of 3 or greater; (2) tracer dissipation is retarded by roughness elements to a greater degree at street level than at rooftop levels; (3) tracer released at street level during moderate winds rapidly disperses to rooftop levels near the release location; (4) tracer released at street level can be channeled down street canyons at angles approaching 60 to 80 degrees from the downwind direction; (5) tracer dissipation is significantly faster during the day than at night; (6) rooftop-level wind speed more strongly influences dissipation rates at night than during the day; (7) street-level turbulence measurements can be useful predictors of tracer dissipation rates; and (8) tracer accumulation and dissipation in underground pedestrian tunnels happens at time scales of at least an order of magnitude greater than those experienced in the open air. All accessible JU03 experimental data are available on the web from archives administered by the U.S. Army Dugway Proving Ground Meteorology Division.

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