P1.4
Perfluorocarbon tracer experiments during VTMX 2000
Jerome D. Fast, PNNL, Richland, WA; and K. J. Allwine, J. C. Torcolini, and R. N. Dietz
A series of perfluorcarbon tracer (PFT) experiments were conducted in Salt Lake valley during October 2000 as part of Vertical Transport and Mixing (VTMX) field campaign sponsored by the U.S. Department of Energy's Environmental Meteorology Program. The PFT experiments were designed to measure dispersion within the urban valley on scales of 5 – 50 km during the nighttime stable conditions and the morning transition period. Four tracers were released, each at a separate location. Two tracers were released south of downtown at a constant rate between 23 and 07 MDT. The other two tracers were released downtown at a constant release rate between 01 and 07 MDT; one at the surface and the other on the top of a building. 2-h samples were collected at 50 sites throughout the valley between 23 MDT and 13 MDT the following day. Three of these sampling locations were on building tops and several were at elevations above the valley floor to determine the vertical extent of mixing during the night. In addition to the 2-h samples, 6 4-h samples were also made to determine ventilation of the valley atmosphere over multi-day periods. In this study, preliminary analysis of tracer dispersion will be presented in the context of the meteorological conditions. The extensive meteorological measurements (wind profilers, sodars, radiosondes, tethersondes, surface meteorological stations, temperature data loggers) collected during VTMX will be used to described the evolution of the 3-D wind and temperatures fields in the valley needed to interpret the tracer data. A mesoscale model that employs a 550-m horizontal grid spacing and a Lagrangian particle dispersion model using conditions prevalent during the PFT experiments will permit comparisons between measured and computed PFT concentrations. The sensitivity to atmospheric processes that affect dispersion during stable conditions will be examined.
Poster Session 1, PBL Processes and Modeling (with Coffee Break)
Monday, 17 June 2002, 2:45 PM-4:15 PM
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