A Monte Carlo algorithm has been developed to investigate the effects of multiple scattering on the volume scattering function measured by the LISST-VSF instrument. The developed algorithm is compared to experimental results obtained from bench-top measurements using 508 nm spherical polystyrene beads and Arizona test dust as scattering agents. The Monte Carlo simulation predicts measured volume scattering functions at all concentrations. We demonstrate that multiple scattered light can be a major contributor to the detected signal, resulting in errors in the measured volume scattering function and its derived inherent optical properties. We find a relative error of 10% in the scattering coefficient for optical depths ∼0.4, and it can reach 100% at optical depths ∼2.

Multiple scattering can severely affect the accuracy of optical instrumentation. Variance reduction methods have been implemented to improve a Monte Carlo model developed to simulate volume scattering functions measured by LISST-VSF instruments. The implemented methods can result in more than a tenfold increase in efficiency. The simulation is used to analyze multiple scattering errors for a range of Fournier-Forand (FF) phase functions. Our results demonstrate significant errors in the scattering coefficient, backscattering coefficient and phase function, where multiple scattering errors may only be considered negligible (<10%) for scattering coefficients <1 m−1. The errors depend strongly on the scattering coefficient but also increase when phase functions become more forward-peaked.