Symposium on Interdisciplinary Issues in Atmospheric Chemistry

J4.6
ALONG-WIND DISPERSION OBSERVED IN THREE FIELD STUDIES

Steven R. Hanna, George Mason Univ, Fairfax, VA; and P. Franzese

The Kit Fox dense gas transport and dispersion field experiment was carried out at the Nevada Test Site in order to improve models for calculating the impact of accidental releases of dense gases during neutral-to-stable conditions within roughness obstacles typical of industrial sites. The 52 carbon dioxide gas releases include both 20-second "puffs" and several-minute "continuous plumes". Extensive observations of vertical profiles of winds, temperatures, and turbulence were taken at five meteorological towers at various points outside and inside the roughness obstacles. One-second concentrations were observed by about 70 monitors on four arcs (25, 50, 100, and 225 m). Vertical profiles of concentration were observed at five levels on three towers on the closest three monitoring arcs. The first part of the analysis involves determination of the best methods for parameterizing the surface roughness length, the friction velocity, the stability, and the wind profile in and above the obstacle arrays. The second part of the analysis involves determination of the characteristics of the carbon dioxide plume (e.g., advection speed and its variation with travel time; lateral, vertical, and longitudinal dispersion; and concentration variation with averaging time at individual monitors and integrated across the wind). The new parameterizations are tested within the framework of the existing HGSYSTEM dense gas dispersion model

Symposium on Interdisciplinary Issues in Atmospheric Chemistry