Satellite observations of the seasonal sediment plume in central East China Sea

Abstract

Ocean color and sea surface temperature (SST) data from the Moderate Resolution Imaging Spectroradiometer on Aqua from 2002 to 2008, wind speed data from the National Centers for Environmental Prediction, satellite-measured sea surface height anomaly (SSHA) data, and World Ocean Atlas 1998 data are analyzed to study and understand the variability of a sediment plume in the central East China Sea, as well as its mechanism for producing this plume. The plume peaks in the winter, with an areal coverage of ∼ 4 × 10 4 km 2 and the diffuse attenuation coefficient at the wavelength of 490 nm ( K d (490)) reaching over 1.5 m − 1 , and almost disappears in the summer. The increase (decrease) of SST is coincident with the K d (490) decrease (increase) during the late spring (fall) and early summer (winter). In the winter, the entire water column becomes uniform with SST ∼ 12 °C in the East China Sea, while in the summer the water column is strongly stratified with SST over ∼ 27 °C. This seasonal sediment plume is attributed to sediment resuspension due to the strong vertical mixing and convection driven by the cooling of the upper ocean and enhanced surface winds during the winter season. In addition, satellite SSHA observations also confirm that the cross-shelf circulation resulting in this plume proposed by Yuan et al. (2008) does not exist.