Design And Calibration Of Polarization Channel In Water Vapor-Cloud-Aerosol Lidar

Lidar with high spatial and temporal resolution has evolved as the mainavoidance approach of atmospheric detection. The lidar team of Ocean University ofChina develops the Water Vapor-Cloud-Aerosol Lidar which assembles the Mie Lidar,Polarization Lidar and Raman Lidar. The lidar system is one of the most peculiarground–based lidar in the world which could detect the all types of water vapor andaerosol.The paper focuses on the design and calibration method in polarizationchannel.Water vapor is the gaseous state of water in the atmosphere, which is the rootcasue of the cloud, rain and snow. The temporal and spatial variation of cloud andaerosol is an uncertain and momentous element for climate and human life. Lidar candetect the thin structures those consist of cloud and aerosol. Polarization Lidar getsthe information of the atmospheric particles by utilizing depolarization ratio of theelastic channel backscattering signal. Some errors exist in the measurements ofdepolarization ratio, including polarization purity, the transmittances difference of theSenkrechit light and Parallel light as well as the cross talk for some optical element,Polarization Gain Ratio (PGR) of two detection channels. The paper emphasizes onthe detection and calibration in Water Vapor-Cloud-Aerosol Lidar, and the analysis ofthe cloud phase and aerosol.The paper introduces the Water Vapor-Cloud-Aerosol Lidar simply and focuseson the channel of polarization, and then analyzes the causes of errors. The opticaldesign software-ZEMAX demonstrates the feasibility of calibration. The secondportion elaborates two methods to obtain the calibration coefficient, including themethod of component measurement and the atmospheric detection.