| In this thesis, methods based on the wavelet transform are used to extend spectral methods for studying turbulent mixing. These methods are then applied to momentum and heat flux for fast response measurements taken above and within a deciduous forest at Camp Borden, Ontario.; Multiscale distributions of flux event intensities are derived, presented and interpreted. Results show intensification of mixing efficiency near the canopy top, dominated by turbulent structures near a dominant scale, as reported in previous studies. There is no indication of a distinct, clearly separable population of intense 'coherent structures', as is often assumed, but rather an overall increase in intermittency near a particular scale.; The multiscale flux event distributions are simplified to provide component cospectra for down-gradient and counter-gradient fluxes. Dimensional arguments are used to explain observed scaling, and differences between upward and downward cospectra of momentum above and within the forest are used to understand the influence of different terms in the Reynolds stress budget.; A multiscale parameterization of the Reynolds stress budget is developed using the wavelet results for momentum flux. The physical meaning of the scale-dependent parameters is examined. Empirical values derived from the Camp Borden observations show considerable consistency. Changes in parameter values within the canopy are consistent with the effect of neglected Reynolds stress budget terms which are known to become significant within the forest. |
