Yang, CY; Ye, HB; Tang, SL (2020). Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing Imagery. REMOTE SENSING, 12(14), 2269.

We evaluated six empirical and semianalytical models of the diffuse attenuation coefficient at 490 nm (K-d(490)) using an in situ dataset collected in the Pearl River estuary (PRE). A combined model with the most accurate performance (correlation coefficient,R-2= 0.92) was selected and applied for long-term estimation from 2003 to 2017. Physical and biological processes in the PRE over the 14-year period were investigated by applying satellite observations (MODIS/Aqua data) and season-reliant empirical orthogonal function analysis (S-EOF). In winter, the averageK(d)(490) was significantly higher than in the other three seasons. A slight increasing trend was observed in spring and summer, whereas a decreasing trend was observed in winter. In summer, a tongue with a relatively highK(d)(490) was found in southeastern Lingdingyang Bay. In Eastern Guangdong province (GDP), the relatively higherK(d)(490) value was found in autumn and winter. Based on the second mode of S-EOF, we found that the higher values in the eastern GDP extended westward and formed a distinguishable tongue in winter. The grey relational analysis revealed that chlorophyll-a concentration (C-chla) and total suspended sediment concentration (C-tsm) were two dominant contributors determining the magnitude ofK(d)(490) values. TheC(tsm)-dominated waters were generally located in coastal and estuarine turbid waters; theC(chla)-dominated waters were observed in open clear ocean. The distribution of constituents-dominated area was different in the four seasons, which was affected by physical forces, including wind field, river runoff, and sea surface temperature.