Estimation of Chromophpric Dissolved Organic Matter Concentration in Erhai Lake Using the Quasi-Analytical Algorithm From Sentinel-3 Satellite Data

Chromophoric dissolved organic matter (CDOM) is a crucial component of aquatic environments. Accurately quantifying the content of CDOM is essential for supporting lake water quality monitoring and management. In this study, we utilized quasi-analytical algorithms (QAA_v6 and QAA_CDOM) to estimate the CDOM concentration in the intricate freshwater environment of Erhai Lake. This was accomplished by utilizing in-situ hyperspectral data and water sample measurements. A quasi-analytical algorithm, named QAA_CDOM_680, was proposed to retrieve CDOM absorption coefficients from Sentinel-3 satellite images by optimizing the reference wavelength based on these two algorithms. The root mean square errors (RMSE) for QAA_V6, QAA_CDOM algorithm, and the new algorithm QAA_CDOM_680 are 0.615, 0.2235, and 0.1935, respectively. The calibration determination coefficients (R2) of the three algorithms are 0.44, 0.51, and 0.63, respectively. The new algorithm demonstrates a significant improvement in accuracy. The results of two satellite-ground synchronous inversions indicate that the calibration determination coefficients (R2) of CDOM absorption coefficients in the Erhai Lake research area are 0.42 and 0.48, respectively. This study has successfully completed the dynamic quantification monitoring of CDOM in Erhai Lake, contributing to the preservation of Erhai Lake’s water quality.