Tide-surge and wave interaction in the Gulf of Maine during an extratropical storm

Abstract

The fully coupled spectral wave and circulation model SWAN + ADCIRC was applied to investigate tide-surge and wave interaction in the Gulf of Maine during the extratropical storm on Patriot’s Day of 2007. Significant tide-surge and wave interaction was found over Georges Bank and in the coastal areas. Over Georges Bank, the wave-induced current reached 0.2 m/s at the storm peak, accounting for 17 % of the total depth-averaged current. In Saco Bay, the current was dominated by wave-induced current with a magnitude up to 1.0 m/s during the storm. Two clockwise circulation gyres were found to form and sustain over a period of 26 hours during the storm in the bay. They were driven by spatial variations of wave height, direction and the resulting wave radiation stress gradient. Wave setup reached 0.2 m at the storm peak along the coast of Saco Bay. In Saco Bay, wave energy dissipation was reduced and wave height increased due to the increased water depth at high tide and surge. Therefore, wave height was modulated by tide and surge accordingly along the coast. As a result, wave setup and wave-induced current in the bay were also modulated by tide and surge. During the tidal cycle at the storm peak, wave setup increased with tidal level and the maximum wave setup coincided with high tide.