A Model Study of the Spectral Structure of Boundary-Driven Rossby Waves and Related Altimetric Implications

Abstract

A two-layer primitive equation box model of the North Pacific Ocean is used to highlight and analyze some general aspects of the linear large-scale boundary-driven oceanic variability that are detectable through altimeter observations. The model is forced by a white-noise wind, and a spectral analysis of the zonal and meridional, barotropic and baroclinic velocity components is carried out. Several dynamical features are identified in terms of boundary-driven Rossby waves, and their spatial structure and frequency dependence are examined theoretically and discussed in connection with recent studies based on altimeter data. In particular, the following aspects of the variability are analyzed: 1) beta-refracted baroclinic Rossby waves, which are found to be generated along the eastern boundary of the ocean by the passage of coastal Kelvin waves originating from the equatorial waveguide, and 2) westward-intensified barotropic Rossby waves, which originate from the western boundary of the ocean after reflection of longer waves generated in midocean. In the discussion the stress is put on dynamical aspects not yet fully understood and on the possibility that altimetry can provide further insight into their functioning.