Uncertainty of atmospheric correction algorithms for chlorophyll alpha concentration retrieval in lakes from Sentinel-2 data

One of the largest uncertainties in remote sensing data comes from atmospheric influence. This research aims to explain the uncertainties emanating from atmospheric correction (AC) product selection and how they influence chlorophyll alpha concentration retrieval in lakes in eastern Lithuania. We tested seven products from six AC processors (Acolite, Acolite Rayleigh, iCOR, Sen2Cor, C2RCC, C2X, and POLYMER) and 10 chlorophyll alpha retrieval algorithms with different architectures. The uncertainty of AC products transferred to chlorophyll alpha concentrations, and large differences in the chlorophyll alpha concentrations retrieved using different AC products were observed. The match-up analysis showed that chlorophyll alpha algorithms based on band difference performed best in terms of a high coefficient of determination and the lowest median bias when used with image-based, Sen2Cor, and TOA data. The results of this study highlight the uncertainties of AC products as well as how the selection of the chlorophyll alpha retrieval algorithm can mitigate the influence of AC selection.