Large-Eddy Simulation of Turbulent Atmospheric Flow within and above a Forest

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The PIs propose to perform large-eddy simulations of the scalar and vector meteorological fields for an atmospheric surface layer extending down to the surface through the canopy layer of tall vegetation such as a forest. The PI has completed and reported a pilot study of such a simulation. The existing code, which has run on a Cray Y-MP, will be the starting point for this project. The model equations solve a time-dependent, 3-dimensional flow field with account taken for the drag of foliage elements and for heat exchange between the air and vegetation. The code will be further developed for optimal simulation of the meteorology of the forest, and output will be tested against published field observations, both in terms of statistical properties and the appearance of organized structures such as ejection/sweep motions and resultant scalar ramps and other spatial patterns. Computed flow fields will be examined in an attempt to link large-scale vorticular structures to signatures observed in time traces at fixed points. Simulations will be performed to determine the influence of forest heterogeneity, such as edge or forest clearing/gap effects on the calculated flow and scalar fields.