A Monte Carlo investigation of the Honey-Wilson relation

Remote sensing of ocean water optical properties is useful because of the potential capability of covering large areas quickly. Passive sensors are most useful for near-surface properties. At greater depths active systems such as LIDAR are potentially better. However, the water properties measured by a LIDAR system are apparent rather then intrinsic. Previous work has shown that even the system attenuation coefficient is not simply related to the beam or diffuse attenuation coefficients. The authors initiated a series of Monte Carlo radiative transfer simulations to further investigate these relations. The starting point is the pair of assumptions: (1) a LIDAR system can measure quantities which can be used to determine k/sub diff/ and k/sub beam/; (2) k/sub diff/ and k/sub beam/ can be related to the absorption (a) and scattering (b) coefficients. By definition, k/sub beam/=a+b. Also, there is the Wilson-Honey empirical relationship (Sorenson, Honey and Payne, SRI Report 5583 (1966)) k/sub diff/=a+b/n where n is empirically determined to be about 6. The authors' first step was to use the Monte Carlo simulations to investigate the conditions of the validity of the Wilson-Honey empirical relationship. They examined the relationship for two albedos and two phase functions. Their initial results show that for an individual albedo the 1/n term is linearly dependent only on the mean scattering angle of the phase function and not on the shape of the phase function.