A 3‐D data‐assimilative tidal model of the northwest Atlantic

Abstract

A three‐dimensional (3‐D) barotropic tidal model for the northwest Atlantic is developed for eight leading semi‐diurnal (M2, S2, N2, K2) and diurnal (K1, O1, P1, Q1) tidal constituents based on the Princeton Ocean Model (POM). Multi‐mission altimetric tidal data are assimilated into the model using a simple nudging scheme. The assimilative model results are validated against independent in situ observations and compared with a non‐assimilative run and previous tidal models. The root‐sum‐square error for the assimilative M2, S2, N2, K1 and O1 tidal elevations is 3.1 cm excluding the Bay of Fundy region and 11.1 cm otherwise. Assimilation improves the accuracy of the model tidal elevation by 40–60% and that of the tidal currents by 20–30%. The semi‐diurnal tidal currents agree better with observations than do the diurnal constituents. The model K1 and O1 tidal currents are intensified on several outer‐shelf areas, qualitatively consistent with shelf‐wave theory and moored measurements, but quantitatively overestimated. Results show that the present assimilative model reproduces the primary tidal constituents better than previous regional and inter‐regional models. In particular, the present model results are as accurate as those of Egbert and Erofeeva (2002) for the northwest Atlantic shelf seas as a whole and better if the Bay of Fundy is excluded, pointing to the importance of the high‐resolution multi‐satellite tides to partially compensate for the simple assimilation technique.