Analysis and classification of flows over gently sloping terrain within patchy vegetation

Many studies have examined flows within and above crops and forests with uniform canopy density. While flows in sparse canopies have gained attention in recent years, many studies have been limited to regularly spaced vegetation, such as what one would find in an orchard. This study examines flows over a gentle slope within patchy vegetation, that is vegetation with varying spatial density dependent on the direction of the approach flow. Velocity and temperature data were collected within and above the patchy canopy at five vertical levels using sonic anemometers over the time period from March 2005 through May 2005. Special attention is given to data processing, particularly the choice of appropriate averaging times and coordinate systems. Mean profiles of velocity, kinematic fluxes, higher order moments, and velocity spectra are analyzed to evaluate how flow characteristics within a patchy canopy fit into the existing framework for surface layer flows. It is found that in spite of the patchiness of the canopy and slope of the terrain, the flow generally behaves as a canopy layer flow.