A note on the locus of a shelf front

Article English OPEN

It is suggested that the locus of a shelf front is where the water depth is equal to the thickness of the tidal frictional bottom boundary layer. From this, it follows that the locus of the front should be given by a critical value of h/Ut, where h is the water depth and Ut is the tidal stream amplitude. This result differs from that suggested by Simpson and Hunter who argued that a critical value of h/U3t determines the locus of the front. The parameterization suggested here implies that the locus of a shelf front (1) does not adjust in response to the seasonal heating cycle and (2) responds only weakly to the spring-neap cycle. Utilizing established empirical constants, we predict that the locus of a shelf front should be where h/Ut ≅ 80 s. All these predicted features conform well with observed properties of shelf fronts. The bottom boundary layer thickness conformant with these results is equal to λ(Cd∫Ut2)1/2/f, where λ = 0.20 and Cd = 0.003.DOI: 10.1111/j.1600-0870.1988.tb00361.x
  • References (9)

    Ekman, V. W. 1905. On the influence of the earth's rotation on Ocean currents. Arch. Math. Astron Phys., Vol. 2, No. 11.

    Garrett, C . J. R., Keeley, J. R. and Greenberg, D. A. 1978. Tidal mixing versus thermal stratification in the Bay of Fundy and Gulf of Maine. AtmosphereOcean 16,40343.

    Landau, L. D. and Lifshitz, E. M. 1959. Fluid mechanics. Course in theoretical physics, 001. 6. Oxford: Pergamon Press, 536 pp.

    Loder, J. W. and Greenberg, P. D. 1986. Predicted positions of tidal fronts in the Gulf of Maine region. Continental Shelf Res. 6, 397414.

    Mofjeld, H.0.and Lavelle, J. W. 1984. Setting the length scale in a second-order closure model of the unstratified bottom boundary layer. J . Phys. Oceanogr. 14, 833-839.

    Simpson, J. H. and Hunter, 1. R. 1974. Fronts in the Irish Sea. Nature 250, 404-406.

    Simpson, J. H. and Bowers, D. 1981. Models of stratification and frontal movement in shelf seas. Deep-sea Res. 28, 727-738.

    Stigebrandt, A. 1985. A model for the seasonal pycnocline in rotating systems with application to the Baltic Proper. J . Phys. Oceanogr. 15, 1392-1404.

    Weatherly, G. L. and Martin, P. J. 1978. On the structure and dynamics of the oceanic bottom boundary layer. J. Phys. Oceanogr. 8, 557-570.

  • Metrics
    No metrics available
Share - Bookmark