EFFECT OF RESIDUAL TURBULENT SCINTILLATION AND A REMOTE-SENSING TECHNIQUE FOR SIMULTANEOUS DETERMINATION OF TURBULENCE AND SCATTERING PARAMETERS OF THE ATMOSPHERE

Physical principles are discussed for measuring both turbulence and scattering parameters of the atmosphere from scintillation measurements by use of a modified direct-detection lidar. The statistics of the backscattered laser-light scintillations are studied, and the conditions for the turbulent regime of lidar signal fluctuations are determined. It is shown that the effect of residual turbulent scintillation may be observed with a lidar equipped with a variable field-of-view receiver. If the lidar focal-plane aperture is smaller than the scale of speckle caused by turbulence, the fluctuations in the backscattered flux coincide with intensity fluctuations of the sounding beam and are not dependent on the size of the receiving aperture. This permits elimination of the averaging effect of the scattering volume and the receiving telescope aperture and permits simultaneous determination of both turbulent and scattering parameters of the atmosphere from lidar measurements. The results of an experimental verification of the method of measuring the turbulence-induced fluctuations of lidar returns with a large receiving aperture are presented, and calculations are given to show the practicality of using this method with existing lidar systems.