89th American Meteorological Society Annual Meeting

Tuesday, 13 January 2009: 1:30 PM
Source emissions and transport and dispersion models for Toxic Industrial Chemicals (TICs) released in cities
Room 124B (Phoenix Convention Center)
Steven R. Hanna, Hanna Consultants, Kennebunkport, ME; and R. Britter, J. Leung, O. R. Hansen, R. I. Sykes, P. Drivas, J. C. Weil, and D. Strimaitis
Poster PDF (934.3 kB)
A review is given of source emissions models for Toxic Industrial Chemicals (TICs), with emphasis on chemicals stored and/or transported as pressurized liquefied gases (e.g., chlorine, anhydrous ammonia, and sulfur dioxide), for which many tons of a gas/aerosol mixture can be released into the atmosphere in one or two minutes. Some recommendations are given for specific source emissions equations, with scientific rationale provided. Field experiments on TIC source emissions are reviewed and some results of evaluations are presented. A hypothetical chlorine railcar release in Chicago is simulated with a CFD model (FLACS) and with several widely-used simpler dispersion models and the results compared. The CFD model-simulated effects of the urban buildings on the dense gas transport and dispersion are discussed, such as constraints by buildings near the source, reductions in transport speed, diversion of the dense gas down drainage slopes, increases in turbulence intensities, and hold-up in building wakes for 30 or more minutes after the main cloud has passed. In addition, results of some sensitivity runs with the SCIPUFF and SLAB models are shown where wind speed, surface roughness, stability, and dry deposition velocity are varied.

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