Multi-source high-resolution satellite products in Yangtze Estuary: Cross-comparisons and impacts of signal-to-noise ratio and spatial resolution

In this study, cross-comparisons of the reflectance at the top of atmosphere (ρ _TOA ), atmospherically corrected water-leaving reflectance (R _rs ), and suspended sediment matter (SPM) concentration derived from three high spatial resolution sensors (Landsat-8/OLI, Sentinel-2A/MSI and GF-1/WFV) were conducted. The purpose was to examine the consistency among multi-source satellite products and their potential to fill the temporal gap of high-resolution satellites time series. Geostationary ocean color imager (GOCI) data and in situ data were used to verify the accuracy and reliability of the high-resolution satellite derived products. The results showed that the ρ _TOA and R _rs data of high-resolution sensors were consistent with GOCI data, especially at the red spectral ranges. The satellite-derived SPM concentrations exhibited good agreement and acceptable errors when compared with both GOCI-derived and in situ SPM data. With regard to the influence of the signal-to-noise ratios, the results showed that the radiometric sensitivities of GF-1/WFV and Landsat-8/OLI were relatively high and presented minimally detectable variations greater than 0.06% in the ρ _TOA and 0.5 mg/L in the SPM concentration for solar zenith angles < 30°. However, the spatial resolution’s impact on the SPM data can be greater than that of the signal-to-noise ratio for turbid waters.