Estimation of Eulerian Sea Surface Currents and Lagrangian Trajectory Using Ocean Color Elements From GOCI Images in Turbid Coastal Water

Abstract

In turbid coastal waters, sea surface currents often exhibit frequent spatiotemporal variability, retrieving them from optical satellite data remains challenging due to the saturated signal caused by suspended particles. This study uses the maximum cross-correlation (MCC) method to retrieve Eulerian currents and Lagrangian trajectories in turbid nearshore areas, and the performance of MCC with different correlation coefficients and tracers are evaluated. Current vectors calculated using the Cosine correlation coefficient show the highest consistency with high frequency radar currents. The minimum average magnitude error and average angular error were 0.51 and 23.98°, respectively. They also demonstrate strong statistical correlations of 0.99 for direction and 0.8 for speed with measured tidal currents, surpassing results calculated using Pearson and Tanimoto correlation coefficients. Eulerian currents and Lagrangian trajectories can effectively be derived from the tracers inverted from Rayleigh-corrected reflectance. The number of valid current vectors from total suspended matter ($R_{rc}\_$TSM) and chlorophyll-a concentration ($R_{rc}\_$Chl) is more than double that estimated with the tracers inverted from thoroughly atmospheric corrected reflectance. The fusion of these two tracers further enhances the reliability and consistency of the estimated currents. In tidal-dominant regions, Lagrangian trajectories from $R_{rc}\_$TSM and $R_{rc}\_$Chl closely match trends in observed tidal currents. Applying the estimated currents, the maximum resuspension rate in Haizhou Bay and northern Subei Shoal is 105.77 mg/(L·h), whereas the maximum deposition rate is 50.78 mg/(L·h). This study enhances the capabilities of high-resolution optical satellite data for observing and analyzing marine environments and physical processes in turbid coastal waters.