Subtidal flow analysis of the Barnegat Bay, New Jersey

Subtidal flow has long been recognized for its influence on transport of light substances such as contaminants and suspended solids in bays and estuaries. Subtidal water level fluctuation and current velocity variation are analyzed in this study at different locations in Barnegat Bay, New Jersey, to understand features of subtidal flow in the bay.; After filtering out high frequency components of data records, including those caused by tidal influence, the Empirical Orthogonal Function method was used to decompose scalar and vector subtidal data sets into two temporally uncorrelated modes of variance. The contribution of each mode of variance at each location was calculated.; The first mode of subtidal current was found to be associated with the first mode of subtidal water level change with time. They described a rise or fall pattern of water level at all points associated with inflow or outflow through bay inlets, respectively. This flow pattern depicts a filling and emptying scenario of the bay driven by coupling with the outer shelf due to wind effect on the coastal ocean, i.e., remote wind effect.; The second mode of water level change and current were associated with the local wind effect on the bay. Wind drives bay water along its way leading to a setup at the downwind point and a set down at the upwind point. The spatial variability of mode 2 at different locations depicts the influence of local wind effect on bay water relative to bay geometry and location of moorings in the bay.; Due to its special importance and role in exchange with the coastal ocean, a characteristic flow curve showing relationship between current and sea level data was established. A mathematical model was additionally derived to estimate the average rate of change in sea level in the Barnegat bay for a given water level at Barnegat Inlet.