Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 1995
Publication Date: N/A
Technical Abstract: The aerodynamic properties of a surface influence the turbulent transfer of momentum, sensible heat, and water vapor. Considerable effort has been devoted to the measurement and estimation of the momentum roughness length (z0) and zero-plane displacement (d) of crop canopies. There is, however, insufficient data on z0 and d for crop residue-covered surfaces. Wind speed and air temperature were measured at six heights above fields with standing corn (Zea mays, L.) stubble approximately 0.3 m-tall. A least-squares regression technique was applied to profile measurements obtained when neutral conditions prevailed for several hours. The log wind profile equation was solved simultaneously for z0, d, and the friction velocity (u*). For the 167 profiles analyzed, z0 and d averaged 15.3 and 169 mm, respectively, over a range of u* from 0.05 to 0.9 m s**-1. Both z0 and d and the surface drag coefficient (Cd) were weakly dependent on wind speed.