The Tidal energetics of Narragansett Bay

Abstract

The average tidal energy budget of Narragansett Bay, a weakly stratified estuary, has been determined from observations of tidal height and current. For average conditions the tidal energy influx to the bay is balanced by the bay's energy sinks, and within the error limits the energy budget balances completely. The average energy inputs to the three bay channels, the West Passage, the East Passage, and the Sakonnet River, are 4.3, 6.4, and 1.1×1013 ergs/s, respectively. Tidal energy is dissipated on the bottom of the bay at the average rate of 8.8×1013 ergs/s, mostly in a few localized areas of high dissipation. The bay does work on the moon at an average rate of 1.8×1013 ergs/s. The energy required for vertical mixing is 0.3×1013 ergs/s. Phase adjustment between tidal height and current is suggested as a mechanism contributing to the instantaneous balance of the tidal energy budget over the lunar cycle.