Free linear solutions of the barotropic shallow-water equations are computed for a variety of basin shapes and topographies relevant to the Pacific Ocean. Attention is drawn to the 2-day to 6-day period band within which large-scale coherency is observed in Pacific tide-gauge records of sea level. In a particular model basin with realistic topography, the fundamental planetary mode of the Pacific occurs with a period of 3 days and four other planetary-topographic modes populate the 4–6 day period band. We argue that the frequencies and structures of these modes are representative of the largest-scale vorticity oscillations of the Pacific and may help account for the observed broad-bandedness of sea-level in the 4–6 day period band. These predictions will guide future analyses of sea-level and bottom-pressure observations from which a direct estimate of the frictional damping of barotopic Rossby waves may ultimately be obtained.
Miller, Arthur J.. 1989. "On the barotropic planetary oscillations of the Pacific." Journal of Marine Research 47, (3). https://elischolar.library.yale.edu/journal_of_marine_research/1943