Spectral and Angular Degree of Polarization of the Water Leaving Radiance from the Ocean

The polarization of the light field reflected from the ocean is now being recognized to contain additional information that can aid in the retrieval of biogeochemical properties of the ocean. But there are currently very few remote sensing systems that can take advantage of this information. We have developed a hyperspectral polarimeter to measure the full linear polarization of the ocean reflectance. The polarimeter uses four lenses with calcite polarizers oriented at 0, 45, 90, and 135 degrees relative to horizontal and measures the linear Stokes vector parameters (I, Q, U) over the spectral range from 350 – 950 nm. The degree and angle of polarization were measured in different water types and found to strongly depend on the inherent optical properties of the water, specifically on the single-scatter albedo, but also phase function, and viewing geometry. We show results for different water types as a function of viewing angle relative to nadir and azimuthal angle relative to the sun. We also show the importance of understanding the effects of the atmosphere on the upwelling polarization signal.