Time-resolved multiple scattering

摘要

Abstract: Time and range resolved multiple-scattered radiation from the aureole around a traveling radiation, using an additional off axis scanning lidar-receiver, on top of an existing lidar. This system can be considered as an analogue equivalent of Bissonnette's fixed multi-field-of-view lidar. Because multiple-scattering is effective over much larger volumes than the illuminating volume by the laser pulse itself; the variations in the signals due to atmospheric structures are reduced to a certain extent. A simple second-order scattering model has been developed to understand this volume averaging effect. It has been shown that this model can be used to estimate the extinction coefficient of clouds and the average diameters of the cloud droplets. Lidar waveforms, obtained during a field experiment, have been inverted with the proposed model. The results appear to be in reasonable agreement with the in situ measured extinction using a nephelometer mounted on a cable car which was moving up and down a mountain slope through the clouds. !12