Investigation of multiple scattering contribution to transmission of radiation in scale model clouds

摘要

A new dual beam laser system was developed for systematic study of the influence of various aerosol parameters such as size, concentration, and refractive index on the transmission of light through an aerosol under well-controlled laboratory conditions. The measuring technique is based on simultaneous observation of transmitted and scattered light fluxes in growing aerosol droplets. Multiple scattering effects were determined by concurrent use of two optical systems for the same model droplet cloud, of which one (the reference system) was negligibly affected by multiple scattering. Modeling of transmittance was performed using a solution of the radiative transfer equation in small angle approximation, as well as Monte Carlo simulations of beam propagation in turbid media. It was found that Monte Carlo results were in good agreement with the experimental data, whereas the small angle approximation considerably underestimated the multiple scattering contributions to the transmitted light for our experimental conditions.