Development of a High Resolution Hydrodynamic Model for the Asian-Pacific, Indian Ocean, and Associated Marginal Sea Basins for Tidal Predictions

The areas of the Western Pacific, Indian Ocean, and their marginal seas (IndWPac) contain significant political, economic, and cultural centers where major storms have global impact. A large-scale, high-resolution grid ADCIRC model of IndWPac is developed, designed to simulate tides to show how well it can capture the significant hydrodynamic exchanges between neighboring basins and to better understand continental shelf dynamics in the domain. The unstructured mesh contains 9.6 million nodes and varies in resolution from 20 km to 100 m.

Several high resolution bathymetry datasets are collected and tested, and errors necessitated numerous depth corrections by referencing digital navigation charts. Dissipative effects are concentrated in two major parameters: bottom friction and internal tide dissipation. Bottom friction parameterization based on seafloor sediment characteristics was developed and found to vary mainly in shallow continental shelf regions, while internal tide dissipation varied in deeper ocean depths. Other tests perturbing bottom friction zone values found that local shelf zones controlled local response of tides.

The best model setup of IndWPac is compared against a collection of 760 tidal observation stations positioned throughout the domain mainly near the coast. A comparison against a global data-assimilated model is made to gauge the IndWPac model’s response in the deep ocean where observations lack coverage. IndWPac model’s errors compare favorably in the nearshore against other hydrodynamic models, and future pursuits for model improvement are suggested.