Determination of turbulent-layer wind speed from G-SCIDAR data using an algorithm based on wavelet transforms

摘要

The determination of turbulent-layers wind speed observed through Generalized SCIDAR technique (G-SCIDAR) requires an efficient and contrasted code. We have developed a fully automated algorithm based on wavelet transforms to derive the velocity magnitude and direction of atmospheric turbulent layers from G-SCIDAR measurements. The algorithm makes use of five cross-correlations of a series of scintillation patterns separated by lapses of Δt, 2Δt, 3Δt, 4Δt and 5Δt. The wavelet analysis of such cross-correlation images provides the position, direction and altitude of the different turbulent layers detected in each image. The comparison and consistency of results in consecutive cross-correlations allows the determination of the turbulence layers velocities and avoids misidentifications associated with noise and/or overlapping layers. The software includes the correction due to the projection effects on the observing direction of the actual velocity vector of turbulence layers. The algorithm has been applied to simulated data with excellent results, as well as to actual G-SCIDAR observations. For the validation of velocities derived for real G-SCIDAR data we have compared them to the velocities provided by balloon measurements. The software has been designed to analyze huge amounts of G-SCIDAR measurements.