Wind speed measurements using distributed fiber optics: a windtunnel study

Abstract

Abstract. Near-surface wind speed is typically only measured by point observations. The Actively Heated Fiber-Optic (AHFO) technique, however, has the potential to provide high-resolution distributed observations of wind speeds, allowing for better characterization of fine-scale processes. Before AHFO can be widely used, its performance needs to be tested in a range of settings. In this work, experimental results on this novel observational wind-probing technique are presented. We utilized a controlled wind-tunnel setup to assess both the accuracy and the precision of AHFO under a range of operational conditions. The technique allows for wind speed characterization with a spatial resolution of 0.3 m on a 1 s time scale. The flow in the wind tunnel was varied in a controlled manner, such that the mean wind, ranged between 1 and 17 m/s. The AHFO measurements are compared to sonic anemometer measurements and show a high overall correlation (0.85–0.98). Both the precision and accuracy of the AHFO measurements were also greater than 95 %. We conclude that the AHFO has potential to be employed as an outdoor observational technique. It allows for characterization of spatially varying fields of mean wind in complex terrain, such as in canopy flows or in sloping terrain. In the future, the technique could be combined with conventional Distributed Temperature Sensing (DTS) for turbulent heat flux estimation in micrometeorological/hydrological applications.