An Optimal Strategy for Applying Combined Atmospheric Correction Approaches to Sentinel-2 MSI Over Inland and Coastal Waters

Reliable atmospheric correction (AC) is a prerequisite for quantitative water color remote sensing. However, the complex and variable optical properties of coastal and inland waters—particularly in regions with spatial intermixing of clear and turbid waters—present significant challenges to achieving stable and consistent results with existing AC algorithms. To solve this problem, this study introduces an atmospheric correction combination strategy for Sentinel-2 MSI, termed Atmospheric Correction Approach combining POLYMER and ACOLITE (ACA<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PO-AC</sub>) , which integrates the strengths of POLYMER in clear waters and ACOLITE-DSF in turbid waters. By constructing a logistic function based on the ratio of near-infrared to green bands, the strategy effectively captures the continuous transition between clear and turbid waters.The performance of ACA<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PO-AC</sub> was evaluated using a global in situ dataset. The results indicate that the ACA<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PO-AC</sub> achieves a coefficient of determination (R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>) exceeding 0.64 for all bands, with (R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>) exceeding 0.77 from 492 nm to 783 nm, and the mean relative percentage deviation (MAPD) for visible bands remaining below 50%. Compared to POLYMER and ACOLITE-DSF, the ACA<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PO-AC</sub> achieved slopes closest to 1 and the lowest bias and root mean square error (RMSE) across all bands (|bias|< 0.0015 sr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup>,RMSE < 0.005 sr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup>).Furthermore, the spatial pattern analyses of R<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rs</sub> and total suspended solids (TSS) confirm that this strategy enables smooth and consistent transitions between clear and turbid waters.