We present results from an experiment to estimate the parameters of homogeneous, isotropic optical turbulence in the upper atmosphere. The balloon-borne experiment made high-resolution temperature measurements at seven points on a hexagonal grid for altitudes from 12,000 to 18,000 m. From the temperature data, we obtained index of refraction fluctuations that can be used to compute a sample-based estimate for a parameterized description of the spatial autocorrelation of the turbulence. The three parameters of interest were a proportionality constant <i>P<sub>C</sub></i>, the power-law parameter α, and the outer scale <i>L</i><sub>0</sub>. The results obtained for <i>P<sub>C</sub></i> are within the expected range and agree well with independent measurements made from a standard rising thermosonde measurement made approximately simultaneously with the data collection. Values for α were in the range 1.52 ≤ α ≤ 1.73 were observed, which are significantly less than the power law used in the Kolmogorov and von Karman models, α = 1.833. Values observed for <i>L</i><sub>0</sub> were in the range 5 ≤ <i>L</i><sub>0</sub> ≤ 190 m. Evidence that α may be consistently less than that used in the Kolmogorov and von Karman models likely has the most significant implications for systems that must work in or through the tropopause.
© 2003 Optical Society of America
(010.0010) Atmospheric and oceanic optics : Atmospheric and oceanic optics
(010.1300) Atmospheric and oceanic optics : Atmospheric propagation
(010.1330) Atmospheric and oceanic optics : Atmospheric turbulence
Jeffrey T. Beyer, Michael C. Roggemann, L. John Otten, Timothy J. Schulz, Timothy C. Havens, and Wade W. Brown, "Experimental Estimation of the Spatial Statistics of Turbulence-Induced Index of Refraction Fluctuations in the Upper Atmosphere," Appl. Opt. 42, 908-921 (2003)