5.3
Higher order turbulent statistics in plant canopies
Kyaw Tha Paw U, University of California, Davis, CA; and M. Falk, R. D. Pyles, R. H. Shaw, and T. King
Higher-order turbulent statistics were measured and modeled for several plant canopies. Measurements were taken at several sites, including at a 65 m tall, 400-600 year old coniferous temperate rain forest in Southern Washington. This site is a long-term AmeriFlux measurement site. At that site three-dimensional, sonic wind velocities and gas concentrations were measured at 10 Hz, 70 m and 3 m above the forest floor. These data were used to analyze second, third and fourth statistical moments of the turbulent quantities. These moments were also estimated using the Advanced Canopy-Atmosphere Simulation Algorithm (ACASA), which consists of a layered canopy radiation model, a physiological model for photosynthesis and stomatal control, a higher-order diabatic turbulence transport model (for longitudinal u and cross-wind v), and a soil mass and energy transport model. Model comparisons with measurements show this higher-order closure scheme yields reasonable results, although some errors are evident. The sensitivity to stability is examined, and comparisons also made for models and measurements for shorter canopies.
Session 5, Canopy micrometeorology
Thursday, 17 August 2000, 8:45 AM-11:15 AM
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