Validation of the 1290 MHz wind profiler at Payerne, Switzerland, using radiosonde GPS wind measurements

The validation of a 1290 MHz wind profiler using 3 years of collocated wind profiler and radiosonde wind measurements is presented. The radiosonde wind information is derived from global positioning system data and is vertically averaged to match the vertical resolution of the wind profiler measurements. The integration period of the wind profiler is chosen such that it is centred around the radiosonde measurement time. Periods where bird migration must be expected have been systematically excluded. The standard deviation of the differences between wind profiler and radiosonde in the wind components u and v is between 1.75 and 2 m s −1 and the bias is smaller than 0.75 m s −1 for heights below 6 km for both modes. Some part of the obtained standard deviation can be explained by the fact that radiosonde and wind profiler measurements are not representative for each other. In order to reduce the representativeness error, a subset of cases has been selected, for which the wind field was stationary during the measurement period and uniform across the sampled volume of the wind profiler. The standard deviation derived from the subset is between 1 and 1.5 m s −1 while the bias changes only little. This reduction can be attributed to a reduction in the representativeness error and in the retrieval error of the wind profiler since atmospheric homogeneity is a basic assumption in the wind retrieval. The obtained value of 1.5 m s −1 can be taken as an upper limit of the measurement uncertainty of the wind profiler in favourable measurement conditions.