Interactions between surface waves and ocean currents over the northwest Atlantic during Hurricanes Earl and Igor (2010) are investigated using a coupled wave‐circulation model and observational data. Our results show that the coupled model improves the model performance in simulating the surface waves, sea level, water temperature, and salinity. By including the wave‐current interactions (WCIs), the maximum significant wave heights (SWHs) are reduced by more than 10% along the storm tracks and more than 20% over eddies. In the Gulf of Maine (GoM), the simulated SWHs and peak wave periods are also modulated by strong tidal currents. Surface waves, in turn, reduce the semidiurnal tidal amplitudes (up to ∼9%) and currents (up to ∼40%) in the GoM due mainly to the wave‐enhanced bottom stress. Surface waves also increase the peak storm surge (up to ∼19%) during these hurricanes, which is mostly attributed to the wave‐induced forces through Stokes drift and wave dissipation but slightly compensated by the wave‐enhanced bottom stress. The hurricane‐driven surface currents are modulated by waves toward the clockwise direction with a decrease in current speeds of more than ∼60%. This is attributed to the reduced current shear and density gradient resulting from mixing enhanced by wave breaking, but compensated by wave‐induced forces. Salinity and temperature are also modulated by surface waves, mostly through the wave‐induced forces and enhanced mixing by wave breaking. Overall, the coupled model produces higher surface salinity and stronger surface cooling due to the inclusion of the WCIs.

An ocean wave model for the northwest Atlantic Ocean based on WAVEWATCH III is used to evaluate four different source term packages (known as ST2, ST3, ST4, and ST6) for the wind input and wave dissipation. The performance of ST2, ST3, ST4, and ST6 is assessed using available measurements from buoy stations and satellite altimeters. The model results for significant wave height ( ${\mathrm{H}}_{\mathrm{s}}$), mean wave period ( ${\mathrm{T}}_{\mathrm{m}02}$), wave spectrum, wind input, and wave dissipation are examined during two periods: (i) winter storms in February and (ii) Hurricane Ophelia in September/October 2011. Analyses of model results demonstrate that ST4 and ST6 have the best performance with an average scatter index within 19.0% for ${\mathrm{H}}_{\mathrm{s}}$ and ${\mathrm{T}}_{\mathrm{m}02}$ in the presence of strong currents and sea ice. These four packages perform differently under different sea states. Package ST6 generally overestimates ${\mathrm{H}}_{\mathrm{s}}$ under the wind-wave-dominated sea states because of strong wind input and fast wave growth but underestimates ${\mathrm{H}}_{\mathrm{s}}$ under swell-dominated sea states because of strong swell dissipation. The effects of ocean surface currents and sea ice on the wave model performance are also investigated. The linear kinematic effects of surface currents on waves can cause non-linear dynamic effects, which can differ among the four packages. Wave scattering in sea ice increases the wave directional spread and may cause an increase in ${\mathrm{H}}_{\mathrm{s}}$. In the presence of sea ice, wind input is reduced and shifted to higher frequencies and wave dissipation is further suppressed.

A coupled wave–tide–circulation model is used to investigate wave–current interactions (WCIs) over the shelf waters of the Northwest Atlantic (NWA) during Hurricane Earl (2010). WCIs have substantial impacts on hydrodynamics in the upper ocean. The significant wave heights are modulated by WCIs, particularly over regions with strong current gradients, with a reduction up to ~2.1 m (20%) during the storm. Noticeable decreases in surface elevations and tidal currents occur in regions with strong tides such as the Gulf of Maine, mainly due to the wave-enhanced bottom stress. Over regions with weak tidal currents, wave effects on currents are dominated by two competitive processes between wave-induced forces and wave-enhanced mixing. The former strengthens surface currents (up to ~0.55 m/s) and increases the peak storm surge (up to ~0.48 m). The latter is responsible for the reduction in storm-induced surface currents (up to ~0.94 m/s) and anticyclonic modulation of current directions. Vertically, WCIs extend the strong vertical current shear and shift it downward during the storm, which enhances the local mixing and changes the structures of near-inertial oscillations (NIOs). Moreover, tidal currents also change the magnitudes of the NIOs and subtidal currents and affect the intensity of WCIs.