Tidal characteristics of the Strait of Magellan

The Strait of Magellan is a 500 km long navigational waterway connecting the South Atlantic and South Pacific oceans. On the Atlantic side, the Strait is characterized by semidiurnal macrotides with mean and spring tide ranges of 7.1 and 9.0 m, respectively. On the Pacific side, tides are mixed, mainly semidiurnal, with mean and spring tide ranges of 1.1 and 1.2 m, respectively. Wide tidal flats and basin geometry tend to amplify the Atlantic shelf tides in the eastern extreme of the Strait. Tidal choking occurs in a series of narrows, causing stepwise decreases in tidal range from east to west. The mean tide range is initially amplified to 8.4 m, then reduced to 4.0 m, and subsequently to 1.2 m within 150 km of the Atlantic Ocean. Peak tidal currents exceed 3 m s −1 in the narrow constrictions and may reach 4.5 m s −1. The tidal form number is 0.12 in the eastern Strait, but exceeds 0.25 less than 125 km from the Atlantic. Bahi´a Gente Grande, an embayment located 165 km into the Strait from the Atlantic, experiences a tidal regime that shifts from semidiurnal to third-diurnal to quarter-diurnal during each month. This regime results from reduction of semidiurnal constituent amplitudes, existence of appreciable diurnal constituent amplitudes, and a four-fold amplification of the M 6 amplitude, which in combination give rise to the double water phenomenon.