Ultrahigh vertical resolution radar measurements in the lower stratosphere at Arecibo

Abstract

We report on heretofore unprecedented observations of the turbulent layers in the Iower stratosphere using the Arecibo 2380-MHz radar. Spectral profiles with about 20 m height and 15 s time resolutions at altitudes in the range 16-19 km are used to parametrize relevant characteristics of the turbulence namely, vertical widths, distributions, lifetimes, and cutoff height. Our measure­ments validate previous deconvolved estimates and are free from contaminating factors like shear or beam broadening and partial reflections. Sorne theoretical predictions are verified, in particular those relating to the height of cutoff and the outer scale of the turbulence. We demonstrate the excellent capabilities of the instrument with observations of wave driven oscillatory displacements of thin turbulence structures near the tropopause. In these circumstances and because of the vertical resolution achieved, it is more direct to describe the inherent variability of spectral features following the vertical displacements of the layers rather than at a fixed height.