D. P. Marshall and H. L. Johnson, Journal of Physical Oceanography, 43, 2699-2717.
Motivated by the adjustment of the meridional overturning circulation to localized forcing, solutions are presented from a reduced-gravity model for the propagation of waves along western and eastern boundaries. For wave periods exceeding a few months, Kelvin waves play no role. Instead, propagation occurs through short and long Rossby waves at the western and eastern boundaries respectively: these Rossby waves propagate zonally, as predicted by classical theory, and cyclonically along the basin boundaries in order to satisfy the no-normal flow boundary condition. The along-boundary propagation speed is c*Ld/delta where c is the internal gravity/Kelvin wave speed, Ld is the Rossby deformation radius and delta is the appropriate frictional boundary layer width. This result holds across a wide range of parameter regimes, with either linear friction or lateral viscosity and a no-slip boundary condition. For parameters typical of contemporary ocean climate models, the propagation speed is coincidentally close to the Kelvin wave speed. In the limit of weak dissipation, the western boundary wave dissipates virtually all of its energy as it propagates towards the equator, independent of dissipation coefficient. In contrast, virtually no energy is dissipated in the eastern boundary wave. The importance of background mean flows is also discussed.
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