Assessing Landsat-8 atmospheric correction schemes in low to moderate turbidity waters from a global perspective

Atmospheric correction is one of the major challenges in ocean color remote sensing,thus threatening comprehensive evaluation of water quality within aquatic environments.In this study,five state-of-the-art atmospheric correction(AC)processors(i.e.Acolite,C2RCC,iCOR,L2gen,and Polymer)were applied to Operational Land Imager(OLI)Landsat-8 scenes and evaluated against in situ measurements across various types of waters worldwide.A total of 262 matchups between in situ measured and satellite-derived remote sensing reflectance(R_(rs))at 20 sites were obtained between August 2013 and August 2021.Classification of optical water types(OWTs)was carried out using in situ measurements with matched satellite observations.OWT-specific analysis demonstrated that L2gen produced the most accurate Rrs with R^(2)≥0.74 and root mean squared error(RMSE)≤0.0018 sr^(–1) for the four visible bands of OLI,followed by Polymer,C2RCC,iCOR,and Acolite.In terms of R_(rs) spectral similarity,C2RCC yielded the lowest spectral angle(SA)of 8.55°,followed by L2gen(SA=9.20°).The advantage and disadvantage of each AC scheme were discussed.Recommendations to improve the accuracy for atmospheric correction were made,such as polarization observations and concurrent aerosol and ocean color measurements.