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NEW DEVELOPMENT IN DISPERSION EXPERIMENTS AND MODELS FOR THE CONVECTIVE BOUNDARY LAYER
Citation:
Weil, J. C., W H. Snyder, R E. Lawson Jr., AND M. S. Shipman. NEW DEVELOPMENT IN DISPERSION EXPERIMENTS AND MODELS FOR THE CONVECTIVE BOUNDARY LAYER. Presented at NATO/CCMS International Technical Meeting on Air Pollution Modeling and Its Application, Boulder, CO, May 15-19, 2000.
Impact/Purpose:
This task objective is the development and improvement of state-of-the-science meteorology models and contributing process parameterizations for use in advanced air quality simulation model systems such as the Community Multi-scale Air Quality (CMAQ) modeling system and for other modeling studies and situations involving transport and dispersion of pollutants. Components of this work include: (a) improved meteorological and transport modeling, (b) improved meteorological modeling physics, (c) physical modeling of flows- building wakes, complex terrain, urban canyons, (d) modeling of transport and dispersion of specialized situations and (e) develop AERMOD (AMS/EPA Regulatory MODel).
Description:
We present recent experiments and modeling studies of dispersion in the convective boundary layer (CBL) with focus on highly-buoyant plumes that "loft" near the CBL top and resist downward mixing. Such plumes have been a significant problem in earlier dispersion models; they are defined by dimensionless buoyancy fluxes F 0.1, where F =Fb/(Uw ?z ), Fb is the source buoyancy flux, U is the mean wind speed, w is the convective velocity scale, and the z is the CBL depth. The chief experimental aim is to obtain statistically reliable mean and fluctuating concentration fields as a function of F and a dimensionless distance X. The experiments are conducted in a convection tank similar to that used by Willis and Deardorff (1987), but with markedly improved data acquisition techniques and statistics.