Seasonal Variability of Diffuse Attenuation Coefficient in the Pearl River Estuary from Long-Term Remote Sensing Imagery

Remote Sensing

Chaoyu Yang¹  Haibin Ye²  Shilin Tang² 

[1] South China Sea Marine Prediction Center, State Oceanic Administration, Guangzhou 510300, China;State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;

关键词: Pearl River estuary;    diffuse attenuation coefficient;    MODIS;    S-EOF;   

DOI  :  10.3390/rs12142269

来源: DOAJ

【 摘 要 】

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, R² = 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 average K_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 high K_d(490) was found in southeastern Lingdingyang Bay. In Eastern Guangdong province (GDP), the relatively higher K_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 of K_d(490) values. The C_tsm-dominated waters were generally located in coastal and estuarine turbid waters; the C_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.

【 授权许可】

Unknown