Statistics of intermediate duration averages of atmospheric scintillation

Abstract

An extensive set of measurements was recently obtained, of the scintillation of a laser propagated over long horizontal paths through atmospheric turbulence, at altitudes spanning the tropopause. These measurements were made over sequences of parallel but displaced paths, like the rungs of a ladder. It is shown here that the intensity reductions due to scintillation of two parallel paths separated by 35.6 meters are partially correlated. Further, the correlations between paths with the discrete experimental separations are used to construct the correlation functions for arbitrary path displacement. The variance in continuous moving averages of the relative intensity is then found in terms of the correlation functions, parameterized by the distance the propagation path is swept through the turbulence. An empirical formulation is developed for use in assessing the expected distribution of intensity reductions in various laser systems. This analysis recovers the statistics of atmospheric scintillation for the important regime in between the two extremes of a snapshot and a long time average.

Atmospheric Intensity Scintillation of Stars, I. Statistical Distributions and Temporal Properties

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