On Planetary Boundary Layer Flow under Conditions of Neutral Thermal Stability

Abstract

A wind spiral model, similar to that proposed by Blackadar, is used to represent the flow above a surface of uniform roughness in the planetary boundary layer (extending up to ?1 km). An attempt is made to determine the applicability of the mixing length model used and to evaluate an empirical parameter used in the model. This attempt, using existing experimental observations of surface shear stress and wind direction, is inconclusive and leads us to suspect that surface inhomogeneity has played a role in some of the experimental data.