Use of Digital Images as a Low-Cost System to Estimate Surface Optical Parameters in the Ocean

Ocean color is the result of absorption and scattering, as light interacts with the water and the optically active constituents. The measurement of ocean color changes enables monitoring of these constituents (dissolved or particulate materials). The main objective of this research is to use digital images to estimate the light attenuation coefficient ([Formula: see text]), the Secchi disk depth ([Formula: see text]), and the chlorophyll a ([Formula: see text] concentration and to optically classify plots of seawater using the criteria proposed by Jerlov and Forel using digital images captured at the ocean surface. The database used in this study was obtained from seven oceanographic cruises performed in oceanic and coastal areas. Three approaches were developed for each parameter: a general approach that can be applied under any optical condition, one for oceanic conditions, and another for coastal conditions. The results of the coastal approach showed higher correlations between the modeled and validation data, with [Formula: see text] values of 0.80 for [Formula: see text] , 0.90 for [Formula: see text] , 0.85 for Chl(a), 0.73 for Jerlov, and 0.95 for Forel–Ule. The oceanic approach failed to detect significant changes in a digital photograph. The most precise results were obtained when images were captured at 45° (n = 22; [Formula: see text]). Therefore, to ensure precise results, the angle of photography is key. This methodology can be used in citizen science programs to estimate Z(SD), K(d), and the Jerlov scale.