Satellite views of the Bohai Sea, Yellow Sea, and East China Sea

Abstract

A comprehensive study of water properties for the Bohai Sea (BS), Yellow Sea (YS), and East China Sea (ECS) has been carried out with 8-year observations between 2002 and 2009 from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua platform. Normalized water-leaving radiance spectra (nLw(λ)), chlorophyll-a concentration (Chl-a), diffuse attenuation coefficient at the wavelength of 490nm (Kd(490)), total suspended matter (TSM), and sea surface temperature (SST) are used to quantify and characterize the physical, optical, biological, and biogeochemical properties and their seasonal and interannual variability in the BS, YS, and ECS regions.The BS, YS, and ECS feature highly turbid waters in the coastal regions and river estuaries with high Kd(490) over ∼3m−1 and TSM concentrations reach over ∼50gm−3. The optical, biological, and biogeochemical property features in these three seas show considerable seasonal variability. The dominant empirical orthogonal function (EOF) mode for Kd(490) and TSM variability in the BS, YS, and ECS regions is the seasonal mode, which accounts for about two-thirds of the total variance. Phytoplankton dynamics in open oceans of the BS, YS, and ECS is also found to play an important role in the Kd(490) variation, while its impact on the ocean turbidity (Kd(490)) is much less than that of seasonal winds and sea surface thermodynamics in coastal regions. The first EOF mode in SST for the regions is seasonal and accounts for nearly 90% of the total SST variance. The major mechanisms that drive ocean color property variations in the BS, YS, and ECS are the seasonal winds, ocean stratification, and sea surface thermodynamics due to the seasonal climate change, as well as coastal bathymetry, seasonal phytoplankton blooms, and river discharges.