Higher order turbulent statistics in plant canopies

摘要

Higher-order closure models which include buoyancy terms have proven themselves complex enough to accurately simulate first- and second-order statistics (Meyers and Paw U, 1987), but simple enough to be incorporated into mesoscale models (Pyles et al., in press). In contrast to flux-gradient (or K-theory) models, counter-gradient and non-gradient transport can be modeled (Meyers and Paw U, 1987). In addition, the diabatic feedback effects of within-canopy biometeorology are directly calculated, which is an improvement over the first canopy higher-order closure methods developed more than two decades ago (Wilson and Shaw, 1977), and also a feature which cannot be directly incorporated into Lagrangian canopy turublence models. Recent modifications have to the model have resulted in the Advanced Canopy-Atmosphere Simulation Algorithm (ACASA), which has been tested for a wide variety of plant canopies ranging from short grass to tall forests, for datasets representing as much as a year of quasi-continuous measurements (Pyles et al., in press). Here, we report the application of ACASA to the 400-500 year old forest at the Wind River Canopy Crane Facility, specifically for estimation of higher-order turbulent statistics.