Supersaturation of fluctuations of waves propagating in a random medium

A theoretical analysis of the incoherent (or fluctuating) component of the wave field radiated by a point source in a one‐dimensional random medium is presented. The approach is based on a perturbation technique which is similar to the Rytov method, and which is referred to here as the quasi‐Rytov method. The analysis includes both multiple forward‐scatter and multiple backscatter effects. An approximate expression for the second moment of the incoherent wave as a function of propagation range is obtained for the case in which the wavelength is much less than the correlation length of the medium. This expression shows that the fluctuations of the wave increase relatively rapidly with propagation range until a maximum value (the supersaturation value) is reached, after which they decrease relatively slowly with further increase in range. These results are in qualitative agreement with observations of intensity fluctuations of optical waves propagating in the lower atmosphere. [Work sponsored by NORDA.]