Analysis of multiple scattering errors in LISST-VSF volume scattering function measurements using Monte Carlo...

Area of Science:

• Ocean optics
• Light scattering in natural waters

Background:

• The volume scattering function (VSF) is crucial for understanding light propagation in aquatic environments.
• Accurate VSF measurements are essential for deriving inherent optical properties (IOPs) and modeling underwater light fields.
• The LISST-VSF instrument is widely used for in-situ VSF measurements, but the influence of multiple scattering is not fully characterized.

Purpose of the Study:

• To develop and validate a Monte Carlo algorithm for simulating multiple scattering effects on LISST-VSF measurements.
• To quantify the impact of multiple scattering on VSF measurements and derived IOPs.
• To assess the accuracy of VSF measurements under varying concentrations and optical depths.

Main Methods:

• Development of a Monte Carlo algorithm to simulate light transport and scattering.
• Bench-top experimental validation using polystyrene beads and Arizona test dust.
• Comparison of simulation results with experimental data across different concentrations.
• Analysis of errors in VSF and derived IOPs as a function of optical depth.

Main Results:

• The Monte Carlo algorithm accurately predicts measured VSFs across all tested concentrations.
• Multiple scattered light is shown to be a significant contributor to the detected signal.
• Relative errors in the scattering coefficient reach 10% at optical depths of ~0.4.
• Errors in the scattering coefficient can exceed 100% at optical depths of ~2.

Conclusions:

• Multiple scattering significantly affects LISST-VSF measurements, leading to potential overestimation of the VSF.
• Inherent optical properties derived from VSF measurements can be erroneous due to uncorrected multiple scattering.
• The developed Monte Carlo algorithm provides a valuable tool for correcting and understanding multiple scattering effects in VSF measurements.