Optical and millimeter line-of-sight propagation effects in the turbulent atmosphere

This paper reviews the effect of clear-air turbulence on line-of-sight electromagnetic propagation, with particular attention paid to remote probing. General relations for the amplitude and phase covariance function of an electro-magnetic wave propagated over a line-of-sight path are given. It is shown that theoretically it is possible to invert measured quantities such as the amplitude covariance function to obtain information about the refractive index spectrum, or the intensity of the refractive index fluctuations along the path. However, it is shown that practical considerations may make these theoretical possibilities difficult to achieve in practice.