Multiple scattering effects in the lidar pulse stretching problem

The lidar pulse stretching phenomenon observed during the 1994 Lidar In-space Technology Experiment (LITE) is investigated in the context of in-cloud photon multiple scattering processes. The single-scatter assumption of the standard lidar equation is insufficient for long-range or wide field-of-view applications, where multiple scattering contributions can become significant. These contributions account for the apparent stretching of the lidar return within optically thick media. Using a Monte Carlo approach, the specific roles of cloud optical properties and instrument geometries in determining the magnitude of pulse stretching are examined. Multiple scattering contributions were found to be significant for lidars operating on the space platform, and pulse stretching of the order of that observed in LITE was reproduced over a wide range of cloud optical parameters. This study seeks to both identify and quantify lidar pulse stretching in terms of these driving parameters.