Tide and surge energy budgets for Eastern Canadian and Northeast US waters

A depth averaged barotropic model is used to quantify the effect of tides and storm surges on the energy budget for the coastal waters bordering the Northwest Atlantic. The model is first shown capable of producing realistic predictions of both tides and surges through comparison with independent sea level observations. In particular, it is shown that the model can predict tidal range with a typical RMS error of 20 cm, and realistic semi-diurnal to diurnal amplitude ratios. Storm surge hindcasts are also shown to be predicted with typical RMS errors less than 8 cm. Following successful validation of the model we produce, for the first time, spatial maps of maximum speed due to combined tide and surge (due to atmospheric forcing) current, tidal only current, and surge only current. The model is next used to examine the energy budget of the study area. It is shown that the energy flux vectors for the semi-diurnal and diurnal tides are very different. O1O1 vectors tends to be more aligned with the bathymetry than the M2M2 vectors. Most dissipation was found to occur in the high tide region of the Bay of Fundy. It is also shown that in the mean (i.e. over a season or a year), surges and tide–surge interaction do not play an important role in the energy budget. However, during a large surge event this is not true; surge and tide–surge interaction can have an order one impact on the energy balance. We discuss how such infrequent and unusually large events impact the nearshore environment.