Radiative transfer simulation of the coupled ocean–atmosphere system is a fundamental tool for developing ocean color algorithms such as atmospheric correction and in-water inversion. The accuracy of the radiative transfer code sets the accuracy limit of the algorithms built with it. This paper describes OCRT (Ocean Color Radiative Transfer), a vector radiative transfer model of the coupled ocean–atmosphere system developed at the Korea Institute of Ocean Science and Technology for ocean color algorithm development, with the Geostationary Ocean Color Imager III (GOCI-III) as the target sensor.

OCRT computes the Stokes parameters I, Q, and U using the successive orders of scattering method over a coupled domain. It includes a molecular atmosphere, Mie aerosol models, a wind-roughened air–sea interface with polarized Fresnel reflection, and a multi-constituent ocean whose water-leaving reflectance is computed from the inherent optical properties of chlorophyll, suspended sediment, and colored dissolved organic matter.

The code was validated against two independent vector radiative transfer codes, Ahmad and Fraser (1982) and OSOAA (Chami et al., 2015), for the Rayleigh atmosphere, the aerosol atmosphere, and the coupled ocean. The code is released as open source to support ocean color algorithm development.