Validation of the dual field-of-view polarization LIDAR technique for the retrieval of homogeneous water cloud microphysical properties: a study based on a polarimetric Monte Carlo simulation

This paper highlights the validation of the dual field-of-view (FOV) polarization LIDAR technique for the retrieval of a cloud droplet effective radius in conjunction with a cloud extinction coefficient of a homogeneous water cloud via a simulation approach. The simulation is based on a polarimetric Monte Carlo method incorporated with semi-analytic features under multiple-scattering conditions. The simulation results show that the depolarization ratio measured at dual-FOVs is a function of the cloud droplet effective radius and cloud extinction coefficient. Using the method of standard deviation on extensive simulation results and then, by applying the polynomial regression, two polynomial relationships are obtained expressing the retrieval of the cloud droplet effective radius and cloud extinction coefficient from the layer integrated depolarization ratio at low optical depths close to the cloud bottom. Eventually, the results presented by Ref. [Atmos. Chem. Phys. 20, 15265 (2020)] are validated. The water cloud microphysical properties, liquid water content, and cloud droplet number concentration are the functions of these two parameters and thus can be found numerically. (c) 2022 Optica Publishing Group