1996 Volume 1996 Issue 67 Pages 33-38
Doppler sodars have been widely used to measure the wind profiles up to several hundred meters. The comparisons with tower instruments show that the Doppler sodars offer the reliable estimations of the mean wind speed (U) and direction (D). From the comparison experiments held at Meteorological Research Institute (MRI), the correlation coefficients are better than 0.9 for U and D, and the rms differences are 0.7-2 mis and 10-25 deg for U and D respectively. An evaluation of the standard deviation of the vertical wind (σDw) is somewhat difficult, but we have the correlation coefficients better than 0.8 and the rms differences of 0.15-0.2 m/s forσDw. Theheavy precipitation and/or the strong wind reduce the maximum detectable height and degrade the accuracy of the wind measurements.
Measurement errors, which seem to be caused by the beam deflection due to refractive changes in the acoustic propagation, prevent the accurate observation of instantaneous horizontal wind velocities. Though thdeviation of the horizontal wind (σDu) can be deduced by the simplified method using the tilted beam axis components, the five-beam phased array Doppler sodar has the capability to measureσu andσv.
