Modeling the Circulation of Manila Bay: Assessing the Relative Magnitudes of Wind and Tide Forcing

Cesar Villanoy, Marilou Martin


A two-dimensional circulation model of Manila Bay was used to determine the relative importance of wind and tide forcing. Tidal forcing was prescribed using tidal curves based on two diurnal (O1 and K1) and two semidiurnal (M2 and S2) components on both sides of the bay mouth. A slight amplitude increase towards the head of the bay was obtained, presumably due to shoaling effects. The high correlation between sea level variations at selected coastal tide stations and model results suggests the dependence on tidal forcing at the mouth. Strongest tidal velocities were found at the mouth and decreased towards the head of the bay. The wind-driven component of the flow using mean September 1995 wind forcing shows the presence of two asymmetrical, counter-rotating gyres. Comparison of wind and tidal kinetic energies indicates the dominance of the wind-driven component of the flow only in selected shallow areas adjacent to the coast.

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