Observations of neutral profiles of wind speed and specific humidity abovea gently rolling landsurface

Analyses were made of wind speed and specific humidity profiles under neutr al conditions obtained by radiosoundings over the gently rolling terrain of the Little Washita Basin, Oklahoma. Inspection of the wind speed profiles showed that the regional (scale of 1 to 10 km) roughness of this basin was z(0) = 0.45 +/- 0.21 m, while the displacement height, d(0), was found to b e 8.9 m. The logarithmic layer of wind speed was observed to occupy the ran ge, (38 +/- 43)z(0) less than or equal to (z - d(0)) less than or equal to (297 +/- 147)z(0) or (0.15 +/- 0.10)h(i) where h(i) is the height of the bo ttom of the capping inversion. This result is comparable with those of prev ious investigations for the lower limit of the range; however, this result also suggests that over this terrain h(i) is the relevant length scale for the upper limit. Evaporation values at the regional scale were computed by combining the wind speed profiles with the specific humidity profiles. Comp arison with surface flux measurements at Bowen ratio ground stations suppor ts the idea that profiles in the neutral atmospheric surface layer aloft at around 100 m above the ground are conditioned by upwind surface characteri stics at the meso-gamma scale.