Variational method for the retrieval of the optical thickness and the backscatter coefficient from multiangle lidar profiles

Applied Optics
Michaël SicardSoon-Chang Yoon

Abstract

A variational method for retrieving the aerosol optical thickness and backscatter coefficient profiles from multiangle lidar measurements is presented and discussed. A monostatic single-wavelength low-energy lidar system was operated at different zenith angles during the Indian Ocean Experiment (INDOEX) campaign in 1999 to characterize the aerosol plumes in the Indian monsoon. The variational method was applied to lidar data to retrieve profiles of optical thickness and the backscatter coefficient for nighttime and daytime measurements. Results are obtained with an uncertainty of 10% below 3 km (nighttime) and 2.8 km (daytime) and a bias of less than 0.01. During daytime the retrieval of optical parameters is indeed limited to a lower altitude owing to the sky background signal and the atmospheric inhomogeneity. In both cases the total aerosol optical thickness is consistent (+/- 10%) with the integrated value derived from sunphotometer measurements. Backscatter-to-extinction ratios estimated in different regions by two distinct methods compared well, which proves the capability of the method to assess optical measurements and account for the altitude dependence of the phase function.

Citations

May 18, 2004·Applied Optics·Markus PahlowMarc B Parlange
Jun 12, 2010·Applied Optics·Francesc RocadenboschAdolfo Comerón
Sep 5, 2012·Applied Optics·Vladimir KovalevWei Min Hao

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