Effects of site relocation and instrument type on recorded wind data characteristics at Wellington Airport

Abstract

Using surface wind speed observations directly without correction for terrain and instrument response characteristics can introduce significant errors in extreme wind speed estimates and other climatological studies. Wind speed measurements collected during 1972 to 2016 at Wellington airport, New Zealand, are the focus of this study. There is a considerable shift in the recorded gust speeds for years after 1993, due to changes in instruments and observing practices, and also the relocation of the mast. In this study, directional gust factors, effective roughnesses, and turbulence intensities at both sites are calculated using the recorded mean and gust data. In addition, by taking into account the response characteristics of the old and new measuring systems, a set of directional correction factors is obtained that can be used to homogenise the historical wind data at this meteorological station. The results show that direct usage of the raw data can lead to wind speed errors of up to about 40%.