The current shear fronts (CSFs) in the East China Sea have been observed during winter in previous studies. In this research, we systematically study characteristics and variation mechanism of the CSFs and its potential effects on the transport of water and suspended sediment and on the inner shelf mud area (ISMA), using the methods of observation data analysis and numerical simulation. The spatial structures, shear intensities, and sea‐land locations of the CSFs are obviously affected by wind, temperature and salinity. The CSFs curve seaward due to the nonuniformity of topography, and the tide causes its periodic and sea‐land shift. The landward U component near the CSFs indicate little cross‐CSF transport (i.e., the barrier effect). The CSFs are important hydrodynamic factors that affect the formation of the ISMA. The periodic shift of the CSFs in the longitudinal direction and its variations in spatial structure are the main mechanisms affecting the spatial distribution and thickness of the ISMA. However, the barrier effect of the CSFs can be interrupted, and both the strong wind in the northeast direction and baroclinic conditions are beneficial for cross‐CSF transport. Furthermore, cross‐CSF transports occur in the upper layers under northwest wind condition, in areas with nonuniformity of topography and during the spring tide period. Three cross‐shelf channels are identified in areas where the CSFs curve seaward resulting from nonuniformity of topography.

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Transport and flux of suspended particulate matter (SPMs) are important but hotly debated topics in the Bohai Sea (BS), Yellow Sea (YS) and East China Sea (ECS). In this study, we calculated the sediment flux and its seasonal variation combining observed suspended sediment concentration (SSC) with numerically simulated currents. Field observations were conducted in the BS, YS and ECS at 43 stations in summer and 46 stations in winter along five transects. HYCOM/NCODA reanalysis data were used to calculate climatologically monthly averaged currents in January and July from 1998 to 2007. The results indicated that a high concentration of SPM moved out of the BS and moved southward into the YS and ECS in winter, with a net sediment flux of 0.12 t/s at the Bohai Strait and 4.37 t/s south of the Yangtze River. In summer, SSC increased from the surface to the bottom layer due to stratification. A southerly wind and stronger warm currents in summer transported SPM from the ECS to the YS and the BS, with a net northward sediment flux of 4.79 t/s at the boundary of the ECS and the YS, and a net sediment flux of 0.08 t/s input into the BS. This study can help to distinguish the contribution of the Yellow River-and Yangtze River-derived sediments to the mud-areas' generation on the continental shelves area of the Yellow Sea and East China Sea.

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