Variation in the Current Shear Front and Its Potential Effect on Sediment Transport Over the Inner Shelf of the East China Sea in Winter

Abstract

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.