Intercomparison of Wind Measurements from Two Acoustic Doppler Sodars, a Laser Doppler Lidar, and In Situ Sensors

Abstract

Intercomparative measurements of wind speed, wind direction, wind direction standard deviation, and vertical wind standard deviation from two acoustic Doppler sodars and a laser Doppler lidar are studied, using the BAO tower to provide reference measurements. Results of wind speed and wind direction comparison indicate that the sodars compare very well with the tower, and that the lidar performs exceptionally well in relation to the tower measurements. Vertical wind standard deviations obtained from the sodars compare reasonably well with the tower estimates. The sodar estimates, however, tended to be smaller, with greater differences found during the day. Wind direction standard deviations from the sodars show very large scatter. The analysis indicates that the measurement inaccuracies arise from a combination of spatial and temporal separations. Study of phase relation between the lidar and the tower measurements of the vertical wind component reinforces the concept of using data transformations for comparing two or more spatially separated sensors that measure the test variables of interest from different domains of the atmosphere.