Optical discrimination of harmful Cochlodinium polykrikoides blooms in Korean coastal waters.

We investigated the possibility of optically discriminating harmful algal blooms (HABs), focusing on Cochlodinium polykrikoides, the major HAB causative dinoflagellate species in Korean waters. We produced a large data set of simulated remote sensing reflectance (R_rs) spectra in a wide range of bio-optical conditions using Hydrolight software and bio-optical data provided by the International Ocean-Color Coordinating Group. The two R_rs band ratios (R_rs(555)/R_rs(531) and R_rs(488)/R_rs(443)) were determined to be effective in discriminating high-density C. polykrikoides blooms. The results were consistent with in situ observations and seem applicable to diverse coastal environments. Our findings provide theoretical and quantitative criteria upon which in-water HAB detecting algorithms can be developed.