Canopy-shear-Layer parameter

A canopy-shear-layer parameter is defined from (6.38),... 

Figure 6.12 Canopy-shear-Layer parameter, CSL, defined in equation (6.39) versus canopy Reynolds number, Re = Uhh/v. Data sources given in Table 6.2. For Katul Pine Uh is not provided, but assumed to be [/ = 1.5 m/s, as in Amiro Pine.

Figure 6.10 Momentum thickness, m, a proxy for shear layer width, and velocity difference, AU/U, where U = (U + I/2)/2. The two parameters are plotted versus distance downstream of canopy edge. Beyond 4-m the shear-layer growth has ceased.

This parameter is similar to one derived by Chu et al.[121] for shallow-shear-layers, with CdCI replacing the bed-friction parameter cf/h. We anticipate that CSL will have a universal value (CSLeq) for obstructed-shear-layers at equilibrium. From Table 6.1 we anticipate CSLeq = 0.21 + 0.03. If this equilibrium exists, then (6.39) can provide an estimate of the length-scale,6e, which defines the region within the canopy that experiences rapid exchange with the adjacent open water (Figure 6.11). The characteristic length-scale of the shear-layer vortices is L = (u)/d(u)/dz, where the sub-script h indicates evaluation at the top of the canopy (at z = h). Substituting into (6.39),... 

---