Data reduction methods for space lidar observation of clouds and aerosols

Abstract

We studied data reduction algorithms for the retrievals of optical properties of cloud and aerosols for a two-wavelength (1053 nm and 527 nm) spaceborne lidar which has been developed in the frame of the Japanese spaceborne lidar project. We simulated cloud and aerosol observations with this lidar for prelaunch characterizations and investigation of the retrieval of cloud and aerosol optical properties. In the simulations, first, lidar return signals were generated for a two-dimensional artificial model atmosphere taking into account all possible noise sources as detector, background radiation, etc. and simulated realistically both the digitized data sampling process and the saturation behavior of the photon counting system. Then, the developed data reduction algorithms were tested with these simulated two-wavelength lidar signals to retrieve cloud and aerosol optical scattering parameters. The results showed that this lidar will provide not only qualitative information of cloud and aerosol distributions but also allows for the quantitative retrieval of optical properties of some aerosol layers and optically thin clouds. Recently, we applied the data reduction methods to the analysis of the data observed by the Lidar In-space Technology Experiment (LITE) in September 1994. The applicability of these methods to retrievals of optical properties of aerosols and optically thin clouds such as cirrus have been demonstrated. Moreover, comparisons of the simulated results for ELISE with the LITE observation were conducted to verify the developed simulation method. In this paper after a brief review of the data reduction algorithms, we present a three-component solution of the lidar equation for data analysis of high level thin clouds with volcanic aerosols and apply it to the LITE data of orbit 125.