Sediment concentration variations in the East China Seas over multiple timescales indicated by satellite observations

Abstract

The suspended sediment concentration (SSC) in the East China Seas (ECSs) is modulated by a host of physical processes such as wind waves, tides, and circulations on different timescales, which in turn lead to SSC variations on the corresponding timescales. However, understanding of SSC variations and their modulation mechanisms remain limited. This study aims to quantify SSC variations on multiple timescales (intratidal, spring-neap, seasonal and long-term timescales) and their modulation mechanisms using high spatial-temporal resolution satellite remote sensing data from MODIS and GOCI. The results indicate that in the ECSs (total area 13.0×10 5 km 2 ), the seasonal variations of wind-waves and ocean stratification play the most important roles in modulating SSC, causing high SSC variation (> 30 mg/L) in 7.33% of the total area, and medium SSC variation (5–30 mg/L) in 31.57% of the total area. Tidal current variations on intratidal timescale play the next most important role, causing high SSC variation in 0.60% of the study area and medium SSC variation in 26.10% of the study area. Spring-neap tidal current variations also have a significant influence on modulating SSC, causing high SSC variation in 0.06% of the study area, and medium SSC variation in 13.10% of the study area. SSC variations on long-term timescale (10 years) are not significant, as strong long-term SSC variations are only observed in an area of 0.0012×10 5 km 2 in the Bohai Sea. These new SSC datasets provide an important new data source to better understand SSC spatial-temporal variability and modulation mechanisms in the ECSs. • Suspended sediment concentration (SSC) in the East China Seas (ECSs) is derived from satellite remote sensing data. • The SSC variations on multiple timescales are quantified based on the high spatial-temporal resolution satellite data. • The modulation mechanisms of SSC variation in the ECSs are analyzed.