Interaction between large and small scales in the canopy sublayer

Two characteristics that distinguish canopy sublayer (CSL) turbulence from its atmospheric surface layer (ASL) counterpart are short-circuiting of the energy cascade and formation of Kelvin-Helmholtz (KH) vortices near the canopy top. These two phenomena lead to nonlinear and poorly understood interactions between small and large scale eddies within the CSL absent from classical ASL turbulence. Using velocity scaling arguments and nonlinear time series analysis, we explore the degree of interaction between large and small scales in a canopy composed of densely arrayed cylinders. We found that such interactions are dynamically divided into four regions depending on the distance from the wall, and posses various degrees of nonlinearity and interaction strengths. The broader impact to CSL Large Eddy Simulations (LES) and low-dimensional dynamical systems (LDDS) models of coherent eddies is briefly discussed. Copyright 2004 by the American Geophysical Union.

Duke Scholars

Author Gabriel G. Katul Civil and Environmental Engineering