Convective Boundary Layer Depth: Improved Measurement by Doppler Radar Wind Profiler Using Fuzzy Logic Methods

Abstract

A new method for estimating the mixing depth of the atmosphere's convective boundary layer is developed for use with wind-profiling radars. This method applies "fuzzy logic" methods to give an improved determination of the atmospheric signal in radar spectra. The method then applies fuzzy logic again to calculate the depth of the convective boundary layer, using vertical profiles of both radar-derived signal-to-noise ratio and variance of vertical velocity. A comparison with independent boundary layer depth observations at two radar wind profiler sites shows that the new method gives significantly more accurate estimates of the boundary layer depth (correlation coefficients of 0.91 and 0.96) than does a standard method (correlation coefficients of 0.14 and 0.80). Also, the new method reduces the absolute error of the mixing-depth estimates to a level similar to the vertical range resolution of the profilers.