Band ratio to band difference for Chl of oceanic waters: broke a self-imposed no-touch zone

Zhongping Lee, Chengfeng Le

There are many empirical algorithms developed for the remote sensing of chlorophyll-a concentration (Chl) from ocean color measurements, with the blue-green band-ratio type of algorithms dominating these practices. During the phase of algorithm development, which is data-driven, generally the errors of remote sensing reflectance (Rrs) from satellites are ignored until Hu et al. (2012) developed a band-difference type algorithm where Rrs at the blue, green, and red bands were used as the input, where the errors in Rrs were kept in mind. This band-difference algorithm generated significantly better Chl image products for oceanic waters from satellite ocean color measurements, which contributed greatly to satellite ocean color remote sensing and influenced the way of thinking in algorithm development.