Stability Dependence of the Ratio of Wind Speeds at Two Levels over Agriculture Land

Abstract

Hourly averaged winds are computed from a one-year record taken atop five 10 m towers and four 30 m towers distributed over 4000 km2 of typical agricultural land. Vertical temperature differences are available from three of the 30 m towers. The ratio of spatially averaged speeds at the two levels is plotted against a mean bulk Richardson number. The range of stability where measurements are possibly consistent with the presence of established similarity profiles is limited and dependent on wind speed. However, the speed ratios follow smoothly varying functional relations over a wide range of stability for each classification of data by season and wind speed.