Long Island Sound estuarine circulation

Wilson, R. E. (1976). Gravitational circulation in Long Island Sound. Estuarine Coastal Mar. Sci. 4, 443-453. 

Fig. iO. Velocity vectors recorded for successive 20-min time intervals by a current meter 2 m above the bottom near the geometrical center of Long Island Sound. The rotary character of the tide and the net drift of bottom water due to the estuarine circulation are shown. 

Strong estuarine circulation at the eastern end of Long Island Sound results in the outflow of surface water and inflow of bottom water through the eastern passes at the rate of about 19,000 m /sec (Riley, 1956), 41 times the fresh water inflow rate. Because these flows are so large, relatively small differences in the concentration of suspended sediment in the surface and bottom water will have a large effect on the calculated net flux through the eastern passes into the Sound. Regular measurements of the sediment concentration in these waters have been made by Bohlen... 

The net westward sand flux has been attributed to the superposition of an estuarine circulation on the strong tidal currents. The way in which this situation results in the net, one-way transport of sand may be made more clear with the aid of a simple representation of the transporting currents and the resulting sediment flux. The currents in Long Island Sound may be decomposed into three components, the long-term mean flow component, the periodic, tidal component, and random variations in the flow. Over short times the bottom currents may be approximated well as a one-dimensional flow in the east-west direction with the tidal component represented by a simple sinusoid so that... 

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