Verification of remote sensing reflectance products and seasonal ocean variation characteristics using the Geostationary Ocean Color Imager II (GOCI-II)

The second Geostationary Ocean Color Imager-II (GOCI-II) onboard the Communication, Ocean, and Meteorological satellite (COMS) has higher reliability and practical value in marine environmental monitoring research compared with polar orbit satellites. Nevertheless, the reflectance products may differ due to the sensor performance differences and ocean colour remote sensing intricacy, especially in high-turbidity coastal areas. Consequently, to verify the authenticity of remote sensing reflectance (${R_{rs}}\left({\rm{\lambda }} \right)$Rrs lambda) products, this paper takes the East China Sea (ECS) with complex and changeable ocean colour elements as the research area, establishes GOCI-II&VIIRS, GOCI-II&MODIS, and MODIS&VIIRS ${R_{rs}}\left({\rm{\lambda }} \right)$Rrs lambda data sets based on the matching principles to evaluate the differences between ocean colour remote sensing products. Results indicate (1) Strong agreement between GOCI-II, VIIRS, and MODIS ${R_{rs}}\left({\rm{\lambda }} \right)$Rrs lambda data exists with significant correlation on the 443 nm, 490 nm, and 555 nm wavelengths; (2) The largest discrepancy was between GOCI-II&MODIS, followed by GOCI-II&VIIRS, and the smallest was amongst MODIS&VIIRS. Furthermore, the seasonal variation of reflectance data and quantitative results were extracted using the coefficient of variations (CVs) of ${R_{rs}}\left({\rm{\lambda }} \right)$Rrs lambda in the ECS in 2021. Compared with MODIS and VIIRS, the CVs of ${R_{rs}}\left({\rm{\lambda }} \right)$Rrs lambda obtained by GOCI-II showed significant stability, especially in summer and winter. The results indicate significant space and time (seasonal) dependence in the ECS, primarily related to its physical and biological optical characteristics.