Optimized remote sensing estimation of the lake algal biomass by considering the vertically heterogeneous chlorophyll distribution: Study case in Lake Chaohu of China

Abstract Due to the difference of vertical distribution of algae in lakes, it is necessary to carry out remote sensing estimation of algal biomass based on the vertically heterogeneous distribution of chlorophyll in order to improve the accuracy of biomass inversion. A new algorithm is proposed and validated to measure algal biomass in Lake Chaohu based on the Moderate Resolution Imaging Spectrometer (MODIS) images. The algal biomass index (ABI) is defined as the difference in remote-sensing reflectance (Rrs, sr−1) at 555 nm normalized against two baselines with one formed linearly between Rrs(859) and Rrs(469) and another formed linearly between Rrs(645) and Rrs(469). Both theory and model simulations show that ABI has a good relation with the algal biomass in the euphotic zone (R2 = 0.88, p