Polarimetric multiple scattering LiDAR model based on Poisson distribution.

Multiple scattering is always present in LiDAR measurements. It is one of the major causes of LiDAR signal depolarization when detecting backscattering from water clouds. For a given probing wavelength, the LiDAR signal is a function of the aerosol size distribution, cloud range, and optical depth, and of the LiDAR field of view (FoV). We present a relatively simple polarimetric multiple scattering model. It uses Poisson statistics to determine the photons' scattering order distribution at a given optical depth and takes into account the aerosol's properties as well as the characteristics of the LiDAR. The results are compared with Monte Carlo simulations performed on two types of cumulus clouds and on a moderate water fog. Good agreement is demonstrated for the total LiDAR signal and the depolarization parameter for a FoV of 1 mrad and a large FoV of 12 mrad.