Modeling Tides in the Alaska Coastal Oceans

Xiaochun Wang (JPL), Yi Chao (JPL), Hongchun Zhang (JPL), Francois Colas (UCLA), James C. McWilliams (UCLA), C. K. Shum (Ohis State Univ.), Yuchan Yi (Ohio State Univ)

With its complex coastlines, islands and shallow inlets, Alaska coastal region provides an extreme testing case for tide and ocean circulation modeling. A three level one-way nested model, configured from the Regional Ocean Modeling System (ROMS), is used to simulate tides of the Alaska region. The finest resolution for the focus area, Prince William Sound, is 1km and 40 levels in vertical direction. The model tidal solution is validated against the multi-satellite altimetry in the open ocean and tide gauges along the coast. The accuracy of barotropic tides, as measured by the root of summed squares (RSS) of the RMS discrepancy of sea surface height amplitudes of eight major tidal constituents, is 11.5cm in the open ocean. Along the coastal region, the RSS of tidal amplitudes is 17.8cm, which is about 10% of the amplitude of the most energetic semi-diurnal constituent M2 of the region. The barotropic tidal energetics of the Alaska coastal region will also be discussed. The addition of tides to the three level nested model is the first step to build a data assimilation and forecasting system for the region.