Method for Estimation of Surface Roughness and Similarity Function of Wind Speed Vertical Profile

Abstract

This study is aimed at identifying and refining a method suitable to estimate the surface roughness length (z0) and the universal similarity function of the wind speed profile (?M) based on ultrasonic anemometer measurements carried out at only one measurement height. This method does not require experimental knowledge of wind speed vertical profiles. It permits the use of experimental data obtained from a single sonic anemometer placed in the surface layer in any stability condition, thereby simplifying experimental campaigns and cost reduction. In a fixed station equipped with a sonic anemometer, it is also possible to obtain a periodic estimate of z0 without additional ad hoc experimental campaigns; thus one can correlate the evolution of this parameter to changes that could be found over the area being studied. To prove its feasibility, the method was applied to data obtained in an experimental campaign carried out in Mexico near the northeast side of Mexico City. An ultrasonic anemometer operating at an altitude of 10 m above surface level was used. The method supplied positive results, thereby confirming its operative usefulness.