Polarization Lidar Calibration Techniques and Sensitivity Analysis

Calibrated lidar measurements of linear depolarization ratio provide highly reliable information to discriminate between spherical and non-spherical particles in the atmosphere and to distinguish between liquid and solid phase clouds. In this paper three different calibration techniques are described. For each technique a sensitivity analysis is performed and the different contributions to the total error are evaluated. The stability of atmosphere, the laser source polarization degree, the accuracy of polarization alignment and the background radiation are taken into account in the simulated depolarization measurements. The influence of these parameters and the choice of calibration range and calibration height are studied also. Two calibration techniques were experimentally validated by more than 28 calibration measurements in nearly 5 months. Furthermore aerosol depolarization measurements taken after the calibration are presented.