Local isotropy in the inertial subrange

Wavelet analysis of longitudinal and vertical velocity components has been performed to investigate local isotropy conditions in the inertial subrange, Analysed turbulence data have been collected in Antarctica. A conditional sampling have been applied to data in order to eliminate intermittency. The conditioned structure functions have been computed to identify the inertial subrange extension through the validation of the K41 similarity relations. The quadrant analysis of the momentum cospectrum allows to locate the low-frequency limit of the isotropic region and to identify the anisotropic eddy motions within the inertial subrange; i.e, the scales associated to the transition from the anisotropy of the energy-containing scales to the isotropy of the small scales. The anisotropy in the inertial subrange can be associated to the direct interaction between large-scale and small-scale motion.