Polarization characterics of underwater upwelling radiance of suspended particulate matters in turbid waters based on radiative transfer simulation

摘要

The polarization of water-leaving radiance (Lw) is more sensitive to microphysical properties (e.g. particles shapes, size distributions, compositions, and refractive index) of hydrosols than the unpolarised radiance. Hence, the polarized Lw can be used to extract additional information on oceanic constituents, which is complementary to the spectral and angular radiance measurements. In this study, the polarization characteristics of underwater upwelling radiance in turbid waters with respect to suspended particulate matters have been investigated. The full Stokes components of the underwater upwelling radiance in the visible spectrum are calculated using a radiative transfer model. And then, the influences of suspended particulate matter concentrations on the directional variations and the polarization of underwater upwelling radiance are examined. The results reveal that the polarization of underwater upwelling radiance (I, Q, U, DOP) shows significant multidirectional variations with respect to observation geometries, wavelengths, and solar zenith angles. Moreover, the polarization of underwater upwelling radiance is highly related to the suspended particulate matter concentrations. It demonstrates the potential of using the polarized signal to retrieve particle concentrations in coastal waters. Therefore, the development of in-situ instrumentations and next generation of ocean color sensors should able to measure the polarization properties of water-leaving radiance are recommended.