Wind and Turbulence in a Sparse but Regular Plant Canopy

Abstract

Wind velocity statistics from several points within a regular but sparse array of clumped corn plants are analyzed, with each clump consisting of 12 plants, having a mean height of 1.6 m and a collective leaf area of about 2.75 m2 and occupying approximately 0.8 m2 of ground area. The clumps defined the (484) nodes of a square lattice, with side length of 5.6 m, and this lattice covered an area of 120 m ? 120 m within an otherwise uniform corn field. Forty-eight half-hour records of daytime mean ?cup? wind speeds and turbulent kinetic energies k, from several points in the canopy, are displayed against a ?reduced? mean wind direction that exploits the symmetries of the canopy. These data conform well with the corresponding fields from a three-dimensional, steady-state wind model (with eddy viscosity ? ?k1/2, where ? is the length scale). Both the observations and the model confirm the importance of a set of special wind directions, some of which place a given point P in the shelter of a nearby clump (?blockage?) and others of which place P in a ?corridor.?