Title

The wave structure function in weak to strong fluctuations: an analytic model based on heuristic theory

Authors

Authors

C. Y. Young; A. J. Masino; F. E. Thomas;C. J. Subich

Comments

Authors: contact us about adding a copy of your work at STARS@ucf.edu

Abbreviated Journal Title

Waves Random Media

Keywords

PHASE FLUCTUATIONS; TURBULENT ATMOSPHERE; OPTICAL SCINTILLATION; PROPAGATION; BEAM; SCALE; Physics, Multidisciplinary

Abstract

The Rytov perturbation method can be used to derive analytic expressions governing statistical quantities of an optical wave propagating through the Earth's atmosphere. It is generally accepted that the validity of these expressions is restricted to the weak fluctuation regime, and that the wave structure function for plane and spherical waves obtained via the Rytov method is valid in all fluctuation regimes, for sufficiently small separation distances. Data from experimental results for the wave structure function as a junction of the fluctuation strength for a fixed value of the separation distance indicate that the Rytov method does not accurately model the behaviour of the wave structure function in moderate to strong fluctuation regimes. This is similar to what is observed for the scintillation index. Recently, however, it was shown that the integral definition of the scintillation index obtained via the Rytov perturbation yields analytic expressions that are valid in all fluctuation regimes when a filter function is applied to the atmospheric spectrum. The underlying physical theory is that as the wave propagates, intermediate refractive index scale sizes fail to refract or diffract the beam. Hence, these scale sizes do not contribute to the scintillation index. In this paper, we investigate the results of applying this concept to the wave structure function. Specifically, we apply a filter function to the atmospheric spectrum and develop analytic expressions for the wave structure function for plane, spherical and Gaussian beam waves using the Rytov perturbation method. It is shown that in weak fluctuations these expressions yield similar results to standard expressions obtained where no filter function is applied. However, in moderate to strong fluctuations, these new expressions predict a decrease in the value of the wave structure function as compared to the standard expressions, following the trend of the experimental data presented by Gurvich.

Journal Title

Waves in Random Media

Volume

14

Issue/Number

1

Publication Date

1-1-2004

Document Type

Article

Language

English

First Page

75

Last Page

96

WOS Identifier

WOS:000188743700007

ISSN

0959-7174

Share

COinS