Decoupling error for the atmospheric correction in ocean color remote sensing algorithms

Abstract

This paper studies the decoupling error associated with the atmospheric correction procedures in the ocean color remote sensing algorithms. The decoupling error is caused by the lack of proper consideration of multiple scattering between the atmospheric and ocean components. In other words, the atmosphere and ocean are not coupled properly. A vector radiative transfer model for the coupled atmosphere and ocean (CAO) system based on the successive order of scattering (SOS) method is used to study the error. The inherent optical properties (IOPs) of the ocean are provided by the most updated bio-optical models. Two wavelengths are used in the study, 412 and 555 nm. For a detector located just above the ocean interface, the decoupling errors range from 0.3% to 7% at 412 nm; and from 0.3% to 3 % at 555 nm for zenith viewing angles smaller than 70°. The decoupling errors are significantly larger for larger zenith viewing angles for this detector. For a detector at the top of the atmosphere (TOA), it is hard to separate the decoupling error from the error introduced by the diffuse transmittance. If we assume the upwelling radiance is uniform just below the ocean surface when estimating the diffuse transmittance, the decoupling errors are from −4% to 8% for zenith viewing angles smaller than 70°; and negative decoupling errors show up at mainly large zenith viewing angles.