Tidal Simulation Using ROMS

Xiaochun Wang (1), Changming Dong (2), Yi Chao (1), and James McWilliams (2)

(1) Jet Propulsion Laboratory, Pasadena
(2) IGPP, UCLA

A three dimensional general circulation model (ROMS) is used to simulate tides along the central western coast of US. The model is three-level nested with the finest resolution of 1.6 km in the Monterey Bay region. The motivation of the study is to test the capability of ROMS in simulating tides and to develop an operational forecasting system for the region. Forced by tidal signal along the open boundaries in west, north ans south directions, ROMS can simulate tidal signal reasonably well in the region. The total error of the amplitudes of eight major constituents, measured by root of summed squares, is less than 6 cm which is about 10% of the amplitude of the most energetic M2 constituent. Fot these major tide constituents, the phase error is less than half hour. A comparison of hourly sea level for August of 2003 shows a RMS error of 8 cm, with slightly less error in the finest model domain. Comparing with barotropic tide models, the tide simulation from a general circulation model is not sensitive to model parameters such as drag coefficient. The addition of tide signal in the ROMS model is a significant step toward an operational forecasting system of the Monterey Bay region.