Computer simulation of wind-driven circulation in a coastallagoon

Recording current meter data, together with ancillarywind data from a 43-day study period in the spring of1980, are used to characterize nontidal motion in general,and the wind-driven current in particular, along the axisof Indian River Lagoon on South Florida's Atlantic coast.Tidal co-oscillations are quantified, then removed fromthe time series to reveal better the response to diurnalbursts in windstress. A cumulative net displacementdiagram shows low-frequency variations in the current datasuperimposed onto a long-term net flow to the south.Cumulative histograms of net displacements over time intervalsof from one to 20 days quantify both extremevalues and the distribution of values between the extremes.Two numerical models are used to simulate winddriven,one-dimensional motion along the axis of thelagoon. Simulated currents from both models are verifiedusing subsurface currents measured 1.6 m above the bottomin 3.8 m of water. A one-layer model indicates substantiallystronger net flow to the north than does a 38-layermodel. Results from both models, suggesting flow to the north, are in conflict with in situ current measurements,which reveal southerly flow during the study period.Freshwater outflow appears to be of primary importance incontrolling the long-term net displacement through thelagoon.