The effect of friction and topography on coastal internal Kelvin waves at low latitudes

Article English OPEN
Romea, R. D. ; Allen, J. S. (2011)
  • Publisher: Co-Action Publishing
  • Journal: Tellus A (issn: 1600-0870, eissn: 0280-6495)
  • Related identifiers: doi: 10.3402/tellusa.v36i4.11641
  • Subject:
    arxiv: Physics::Geophysics | Physics::Fluid Dynamics | Physics::Atmospheric and Oceanic Physics | Astrophysics::Cosmology and Extragalactic Astrophysics

The effects of bottom Ekman layer friction and slope topography on freely propagating coastal internal Kelvin waves in a stratified ocean are examined. Frictional effects are assumed weak and specific slope topographies are chosen so that perturbation methods may be used to obtain solutions. Two models for slope topography are utilized: a steep slope model, which corresponds to the low latitude case where the Rossby radius scale δR is assumed large compared to the slope width Ls, and a weak slope model, which corresponds to the case δR≪Ls. For both cases, internal Kelvin waves are damped by bottom friction, and offshore and vertical phase lags are induced, as well as an onshore flow. However, there are substantial differences between the results obtained with the two different models. For example, vertical phase shifts due to friction for the steep slope case imply that alongshore velocity v at the surface leads v below, while motions at the bottom lead for the weak slope case. For the weak slope, frictional effects are proportional to bottom velocity, implying that, for mid-latitudes, bottom stress effects on barocline modes are minimal. However, results from the steep slope model imply that baroclinic modes are significantly affected by bottom stress at low latitudes. In both cases, the topography changes the frequency and alongshore phase speed of the wave, the modal structure is altered, and an onshore flow is induced. For the weak slope case, the wave speed is proportional to the mean bottom depth averaged over the Rossby radius scale. For the steep slope, changes in wave speed depend on the details of the slope geometry: a slope that is concave downward increases the speed while a slope that is concave upward decreases the speed. Both models are compared with observations from the Peru coast.DOI: 10.1111/j.1600-0870.1984.tb00256.x
  • References (22)
    22 references, page 1 of 3

    Allen, J. S. 1973. Upwelling and coastal jets in a continuously stratified ocean. J. Phys. Oceunogr. 3, 245-257.

    Allen, J. S. 1975. Coastal trapped waves in a stratified ocean. J. Phys. Oceunogr.5,30&325.

    Allen, J. S. and Romea, R. D. 1980. On coastal trapped waves at low latitudes.J. Fluid Mech. Y8.555-585.

    Alkn, J. S. and Smith, R. L. 1981. On the dynamics of wind-driven currents. Phil. Truns. R. Soc. Lond. A 302.6 17-634.

    Brink, K. H. 1982a. A comparison of long coastal trapped wave theory with observations off Peru. J. Phys. Oceunogr. 12,897-9 13.

    Brink, K. H. 3982b. The effect of bottom friction on low frequency coastal trapped waves. J. Phys. Oceunogr. 12,127-133.

    Brink, K. H. and Allen, J. S. 1978. On the effect of bottom friction on barotropic motion over the continental shelf. J. Phys. Oceunogr. 8.9 19-922.

    Brink, K. H., Allen J. S.and Smith, R. L. 1978. A study of low frequency fluctuations near the Peru coast. J. Phys. Oceunogr. 8, 1025-1041.

    Brink, K. H., Halpern, D. and Smith, R. L. 1980. Circulation in the Peruvian upwelling system near I 50° S. J . Geophys. Res. 85,4036-4048.

    Brink, K. H. and Allen, J. S. 1983. Reply. J. Phys. Oceunogr. 13, 149- 150.

  • Metrics
    No metrics available