Comparison of Wind Monitoring Systems. Pad II: Doppley. Sodars

Abstract

Measurements of wind speed, wind direction, and the vertical component of turbulence, from four different commercially available Doppler sodars, are compared with similar measurements from in situ sensors on a 300 m instrumented tower. Results indicate that the four sodars measure wind speed and direction accurately and with reasonably high precision. The sodars tended to overestimate the vertical component of turbulence at night and to underestimate it during the day. Precision in those measurements was considerably poorer than for the averaged speeds and directions. Analysis of the vertical wind speed measurements from the sodars indicates that the measurement inaccuracies arise from a combination of aliasing and spatial averaging. Comparison of five in situ wind systems with a sonic anemometer are presented in Part I of this two part series of papers.