Barotropic tides of the Chilean Inland Sea and their sensitivity to basin geometry

The eight major tidal constituents of the Chilean Inland Sea (CIS, 41°–47°S) are simulated using the Regional Ocean Modeling System. In general, the simulated amplitude and phase of each constituent agree with those observed at various locations within the CIS to within 7 cm and 14°, respectively. In particular, the model simulates the major tidal constituent (M2) to within 1% in Puerto Montt, the location of maximum tidal amplitude, and within 5% elsewhere. Distinctions are seen between the character of the tide in the northern and southern sections of the CIS. The character of tidal propagation in the northern CIS is seen to share many of the properties of a forced damped channel with a resonant frequency of approximately 10 h −1 , i.e., slightly higher than that of the shortest period semidiurnal tide. In contrast, the southern CIS does not respond as a forced channel due to the possibility for tidal propagation through the Chonos Archipelago, and as a result tidal amplitudes are smaller, and phase more homogeneous, than in the northern CIS. A series of additional simulations, together with the analytical solution for a harmonically forced branched channel, reveal that the modeled tides are highly sensitive to the resolution of the CIS's complex coastal geometry. In particular, it is found that under‐representation of the channels leading to the open ocean can cause CIS‐wide changes in M2 tidal amplitude and phase, highlighting the importance of these channels to the character of the tide in the CIS.