Profiles of Wind and Temperature from Towers over Homogeneous Terrain

Abstract

Wind and temperature Profiles from three towers were examined under conditions of fairly homogeneous fetch. With numerically small Richardson numbers, no significant deviations from logarithmic profiles were detected up to 150 m. Under non-neutral conditions, Monin-Obukhov scaling described the profiles well, provided that surface values of the scaling parameters were used. Nondimensional wind profiles in stable air agree well with corresponding profiles in the surface layer. In unstable air the nondimensional functions deviated slightly from the functions found near the ground. In particular, for large |z/L|, ϕm approached |z/L|&minus½ rather than |z/L|−¼ Nondimensional temperature profiles showed some systematic differences from the corresponding profiles near the ground. In a few cases the lapse rate reversed above some height, so that the normalized temperature gradient became negative. Abstract Wind and temperature Profiles from three towers were examined under conditions of fairly homogeneous fetch. With numerically small Richardson numbers, no significant deviations from logarithmic profiles were detected up to 150 m. Under non-neutral conditions, Monin-Obukhov scaling described the profiles well, provided that surface values of the scaling parameters were used. Nondimensional wind profiles in stable air agree well with corresponding profiles in the surface layer. In unstable air the nondimensional functions deviated slightly from the functions found near the ground. In particular, for large |z/L|, ϕm approached |z/L|&minus½ rather than |z/L|−¼ Nondimensional temperature profiles showed some systematic differences from the corresponding profiles near the ground. In a few cases the lapse rate reversed above some height, so that the normalized temperature gradient became negative.