Effect of aerosol and multiple scattering on polarisation of skylight during twilight

摘要

A relation between the degree of polarization at the zenith during twilight under cloudless condition and the aerosol content variations in the troposphere and stratosphere was found experimentally in the work of Shah (1969).Later papers,Belying and Daren (1988),Postylyakov et.al (200 lb) and others,discussed an opportunity to determine the vertical distribution of aerosol scattering using twilight measurements.The essential trouble in solution of the raising aerosol inverse problem is allowance for multiple scattering of light,which has the same depolarizing effect like the aerosol.Analytical investigations (Fesenkov,1966,Ugolnikov,1999,Ugolnikov and Maslov,2002) proposed approaches to evaluate a part of multiple scattering light in the polarization.The main goal of this investigation is to separate effects of aerosol and multiple scattering in polarization of skylight,basing on comparison of field observations of polarization and a radiative transfer simulation with account of multiple scattering.