Characteristics of stratospheric turbulent layers measured by LITOS and their relation to the Richardson number

摘要

abstract_textpBased on high-resolution turbulence measurements performed with the newly established balloon-borne instrument Leibniz Institute Turbulence Observations in the Stratosphere (LITOS) during the Balloon Experiments for University Students (BEXUS) 6 and BEXUS 8 campaigns from Kiruna, we derived characteristics of stratospheric turbulence layers, like their thickness and distance in between. Typically, the layers are similar to 15-130 m thick and have a distance of similar to 60-270 m, and their number increases with altitude. Due to the very high measurement resolution of LITOS in the range of millimeters, we obtain energy dissipation rate profiles with unprecedented precision. Within the turbulent layers we get a mean dissipation rate of 3.4x10(-2) W/kg (BEXUS 6) and 1.1x10(-2) W/kg (BEXUS 8) corresponding to a heating rate of 1 to similar to 3 K/d. The profiles show an increase of the energy dissipation with altitude. Comparisons with the Richardson number Ri preclude a clear correlation between the occurrence of turbulence and Ri 1/4. Despite the expected occurrence of turbulence at Ri 1/4, we also observed turbulent layers where Ri was 1/4 and far beyond, independent of the scale over which Ri has been determined./p/abstract_text