Finite‐amplitude stability of a topographically forced wave with Ekman dissipation

摘要: The linear and finite-amplitude stability characteristics of a topographically forced wave are examined in quasigeostrophic, viscous, barotropic model on beta-plane. analysis reveals that amplification superimposed disturbance is favored when the approximately 90° out phase with topography. This relationship corresponds to flow near topographic resonance. amplitude evolution weakly unstable characterized by monotonic approach steady value as it reaches finite amplitude. nonlinear equilibrating mechanism convergence momentum flux which results from interacting correction wave, its higher harmonics, form drag induced mean flow. In absence secondary zonal wavenumber field, threshold for given set parameter values minimized, equilibration at solely interactions involving harmonics. Finite instability shown exist certain restricted regions space. DOI: 10.1111/j.1600-0870.1987.tb00292.x