Spectrum analysis of wind profiling radar measurements

Abstract

Unlike previous studies on wind turbulence spectrum in the planetary boundary layer, this investigation focuses on high-altitude (1–5 km) wind energy spectrum and turbulence spectrum under various weather conditions. A fast Fourier transform (FFT) is used to calculate the wind energy and turbulence spectrum density at high altitudes (1–5 km) based on wind profiling radar (WPR) measurements. The turbulence spectrum under stable weather conditions at high altitudes is expressed in powers within a frequency range of 2 × 10−5–10−3 s−1, and the slope b is between −0.82 and −1.04, indicating that the turbulence is in the transition from the energetic area to the inertial sub-range. The features of strong weather are reflected less obviously in the wind energy spectrum than in the turbulence spectrum, with peaks showing up at different heights in the latter spectrum. Cold windy weather appears over a period of 1.5 days in the turbulence spectrum. Wide-range rainstorms exhibit two or three peaks in the spectrum over a period of 15–20 h, while in severe convective weather conditions, there are two peaks at 13 and 9 h. The results indicate that spectrum analysis of wind profiling radar measurements can be used as a supplemental and helpful method for weather analysis.