Wednesday, 14 January 2009: 2:00 PM
Development of a vegetation deposition model for a fast response urban Lagrangian dispersion model
Room 124B (Phoenix Convention Center)
Over the last few years, a tremendous amount of work has gone into the development of building resolved urban flow and dispersion models for both fast response and basic knowledge applications. Most of these models however, do not explicitly include vegetation even though many built environments have significant vegetated regions in the form of deep continuous plots (e.g., parks), individual trees (e.g. tree-lined streets) or highly interspersed with homes (e.g. suburban neighborhoods). The role of the vegetation on transport and dispersion is particularly important for transport near sources where the concentration flux is largely horizontal and deposition to vegetation is not well represented by classical resistance network formulations. For this work, a general vegetation deposition model for a Lagrangian dispersion model has been developed and applied within the framework of the QUIC dispersion modeling system. Mean wind, turbulence and deposition models for relatively deep vegetative canopies are presented. In this model, the individual vegetation components (leaves, stems, etc.) of canopies are not explicitly resolved, but are modeled in a bulk sense. The deposition model is an extension of the Raupach et al. (2001) model designed for windbreaks and includes a spatially varying leaf area index. The results are compared to field data for an elevated line release of spores in a wheat canopy.
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