Two-dimensional hydrodynamic modeling of circulation in Great South Bay and New York Bight

• Hydrodynamic model for Great South Bay and New York Bight is validated with observations.
• Subtidal currents with speeds of 10–20 cm/s are generated due to winds.
• Subtidal currents must be included in the pollutant transport and oil spill models for Great South Bay.

A two-dimensional depth-averaged boundary-fitted hydrodynamic model is used to study circulation in Great South Bay and New York Bight Region. The model domain included portions of New York Bight from Cape May, New Jersey to Montauk Point at the end of Long Island Sound, New York Harbor, Great South Bay and the adjoining rivers in New York and New Jersey. The model forcing functions consisted of tidal elevations along the open boundaries and winds. Model predictions of surface elevations at Fire Island Inlet and Moriches Inlet Coast Guard Stations showed good comparison with observations, with correlation coefficients exceeding 0.960. The simulated tidal currents showed good comparisons with observations with root mean square errors less than 10% and correlation coefficients exceeding 0.910. The model predicted low-frequency currents showed favorable comparison with observations, with correlation coefficients of 0.808 and 0.605, respectively for the east–west and north–south components. Observations and model simulations show that the subtidal currents with speeds of 10–20 cm/s are generated due to alongshore wind over the continental shelf.