Semianalytical Derivation of Phytoplankton, CDOM, and Detritus Absorption Coefficients From the Landsat 8/OLI Reflectance in Coastal Waters

The Operational Land Imager (OLI) onboard Landsat 8 has potential for mapping the water bio‐optical properties with high spatial resolution. Landsat 8/OLI generates the remote sensing reflectance ( R rs ) at four visible bands ( λ 1‐4 = 443, 482, 561, and 655 nm) and is lack of a 412‐nm band commonly included for ocean color sensors. This spectral configuration has limited the use of Landsat 8/OLI reflectance product for analytical derivation of light absorption coefficients of phytoplankton, colored dissolved organic matter (CDOM), and detritus. In this study, we proposed a hybrid approach to fill this gap. First, we developed an algorithm to estimate the reflectance in a virtual band centered at λ 0 = 412 nm from the OLI reflectance spectra R rs ( λ 1‐4 ). Both the estimated R rs ( λ 0 ) and measured R rs ( λ 1‐4 ) were then used together to retrieve the water component absorption coefficients with existing algorithms including the quasi‐analytical algorithm. We assessed the model performance using in situ measurements from the global waters. It was found that the proposed approach could estimate R rs (412) with a median absolute percentage difference of ~9%. The subsequent retrievals of the component absorption coefficients were satisfactorily accurate, with median absolute percentage difference roughly equal to 35%, 40%, and 60% for phytoplankton, CDOM, and detritus, respectively. The results suggest the feasibility to generate analytically the component absorption coefficients from the Landsat 8/OLI reflectance.