Abstract:
Several types of cup anemometers with considerably different designs and recording systems have been used in New Zealand during various periods. The changes in instrumentation and observing practices have affected the recorded wind speeds and resulted in inhomogeneous historical data. In this study, wind-tunnel tests were carried out to compare the response characteristics of three main cup anemometers utilised in New Zealand, using random process and linear systems theory. Different parameters, such as distance constants of the anemometers, peak and gust factors, are determined at different turbulence intensities and wind speeds. The average expected gust factor ratios between these anemometers are calculated, and the effect of applying the WMO-recommended 3-s moving average on the recorded gusts are investigated. It is generally found out that the Vector and Vaisala anemometers record 7%-13% and 9-15% higher gusts than those of the Mark II Munro anemometer, respectively, and applying the WMO 3-s moving average reduces these differences to about 1% to 6%.