Assessment of the impact of local surface heterogeneity on atmospheric boundary layer with large-eddy simulations (LES) over remotely-sensed surfaces
Vijayant Kumar, Johns Hopkins University, Baltimore, MD; and M. Parlange, C. Meneveau, T. J. Schmugge, and W. P. Kustas
A computational study of the atmospheric boundary layer over remotely-sensed heterogeneous terrain is performed using large-eddy simulation (LES). A scale-dependent version of the Lagrangian Dynamic subgrid-scale model has been implemented in the LES thereby improving the predictions of the turbulence structure especially in the near-wall region. The heterogeneous terrain is implemented using remotely-sensed datasets of surface roughness and skin temperature from the USDA-ARS El Reno experiment. The second order structure function is used to determine the characteristic length scale of the various remotely-sensed datasets and LES runs using datasets with a variety of characteristic length scales are performed. Additional simulations using homogeneous boundary conditions are also performed where the boundary condition is prescribed as the mean of the remotely-sensed dataset. A blending height analysis is performed to distinguish between the variability induced by the local surface features and the random variability inherent to boundary-layer turbulence. .
Session 9, Surface layer interactions, fluxes, and heterogeneity (Parallel with Session 10)
Thursday, 12 August 2004, 1:30 PM-5:45 PM, Vermont Room
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