Validation Test Report for the Tidal Open-Boundary Prediction System (TOPS)

This Validation Test Report presents tests of the use of the Oregon State University (OSU) Tidal Inversion Software (OTIS) to provide tidal boundary conditions (BCs) for the Navy Coastal Ocean Model (NCOM) in several regional and coastal domains. OTIS is a set of programs designed to generate optimal tidal solutions within an ocean domain by 4D variational assimilation of tidal data from various sources, including satellite altimetry and coastal tide gauges. The procedure used to generate tidal BCs is that OTIS is run on the grid used by NCOM to generate a tidal solution for that domain, and values from the OTIS solution are used to provide tidal BCs for NCOM. The tides generated by NCOM with BCs from OTIS and from existing regional and global tidal data bases are compared. Tidal errors are computed by comparison of the tidal solutions with coastal tide-gauge and satellite altimeter data. For large ocean domains, using tidal BCs from OTIS and from existing tidal data bases gave comparable errors. For smaller domains, using tidal BCs from OTIS gave a small improvement, overall, compared to using BCs from the tidal data bases. The OTIS tidal solutions, themselves, generally provide more accurate tides than the tidal data bases in small, coastal domains.