Modeling the inherent optical properties of aquatic particles using an irregular hexahedral ensemble

- The nonspherical effects on the backscattering-related and polarimetric scattering properties of aquatic particles are examined.
- Interpretation of measured backscatter of aquatic particles using a spherical model may give rise to considerable errors.
- The feasibility of a hexahedral ensemble is validated in comparison with measurement.

A statistical approach in defining particle morphology in terms of an ensemble of hexahedra of distorted shapes is employed for modeling the Inherent Optical Properties (IOPs) of aquatic particles. The approach is inspired by the rich variability in shapes of real aquatic particles that cannot be represented by one particular shape. Two methods, the Invariant Imbedding T-matrix (II-TM) and Physical Geometric Optics Hybrid (PGOH) method, are combined to simulate the IOPs for aquatic particles of sizes ranging from the Rayleigh scattering to geometric optics regimes. Nonspherical effects on the IOPs are examined by comparing the results with predictions based on the Lorenz-Mie theory to explore the limitations of assuming the particles to be spherical. We pay special attention to backscattering-related and polarimetric scattering properties, particularly the backscattering ratio, Gordon parameter, backscattering volume scattering function and the degree of linear polarization. The simulated IOPs are compared with the in-situ measurements to assess the feasibility of using a hexahedral ensemble in modeling the IOPs of the aquatic particles.