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Coastal upwelling on a sloping bottom: the formation of plumes, jets and pinched-off cyclones

Published online by Cambridge University Press:  21 April 2006

S. Narimousa  and
T. Maxworthy
S. Narimousa
Affiliation:
Department of Mechanical Engineering, University of Southern California, Los Angeles, CA 90089–1453, USA
T. Maxworthy
Affiliation:
Department of Mechanical Engineering, University of Southern California, Los Angeles, CA 90089–1453, USA
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Abstract

An experimental, two-layer, stratified model of coastal upwelling was produced at the outer edge of a cylindrical tank having a conical bottom. As in Narimousa & Maxworthy (1985), we find that most of the characteristics of the flow field can be described by the single non-dimensional parameter θ* = g′h0/μ*fλs (where g′ = gδP is the reduced gravity, h0 is the initial depth of the top layer, μ* is the friction velocity applied to the top surface of the fluid, f is the Coriolis parameter and λs is the distance of the stationary position of the upwelling front at the surface from the wall of the tank). For example, we find that the migration rate of the front at the surface, μf is given by μf/μ* ∼ θ−½*; the size λW of the frontal, circular waves is λW/λs ∼ θ*; that these waves first appear at the front when it has moved a distance λi < λs given by λi/λs ∼ θ−½*; and have a final drift velocity μw ≈ 0.5 U in the direction of the applied stress (where U is the mean velocity of the top layer). At low values of θ* complex interactions between the growing waves created intense meandering jets which transported upwelled fluid far from the mean position of the front.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 176 , March 1987 , pp. 169 - 190
Copyright
© 1987 Cambridge University Press

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References

Bernstein, R. L., Breaker, L. & Whirtner, R. 1977 California current eddy formation: ship, air and satellite results. Science 195, 353–359.Google Scholar
Breaker, C. L. & Mooers, C. N. K. 1985 Oceanic variability off the central California coast. Prog. Oceanogr. (submitted).Google Scholar
Brink, K. H., Jones, B. H., Van Leer, J. C., Mooers, C. N. K., Stuart, D. W., Stevenson, M. R., Dugdale, R. C. & Heburn, G. W. 1981 Physical and biological structure and variability in an upwelling center off Peru near 15 S during March. 1977. In Coastal Upwelling (ed. F. A. Richards), pp. 473–495. AGU.
Brink, K. H., Halpern, D. & Smith, R. L. 1980 Circulation in the Peruvian upwelling system near 15s. J. Geophys. Res. 85, 4036–4048.Google Scholar
Chia, F. R., Griffiths, R. W. & Linden, P. F. 1982 Laboratory experiments on fronts. Part II. The formation of cyclonic eddies at upwelling fronts. Geophys. Astrophys. Fluid Dyn. 19. 189–206.Google Scholar
Douglas, R. A., Hide, R. & Mason, P. J. 1972 An investigation of the structure of baroclinic waves using three-level photography. Q. J. R. Met. Soc. 98, 247–263.Google Scholar
Eady, E. T. 1949 Long waves and cyclone waves. Tellus 1, 35–52.Google Scholar
Flament, P., Armi, L. & Washburn, L. 1985 The evolving structure of an upwelling filament. J. Geophys. Res. 90, 11783–11798.Google Scholar
Griffiths, R. W. & Linden, P. F. 1981a The stability of vortices in a rotating, stratified fluid. J. Fluid Mech. 105, 283–316.Google Scholar
Griffiths, R. W. & Linden, P. F. 1981b The stability of buoyancy driven coastal currents. Dyn. Atmos. Oceans 5, 281–306.Google Scholar
Griffiths, R. W. & Linden, P. F. 1982 Laboratory experiments on fronts. Part I. Density driven boundary currents. Geophys. Astrophys. Fluid Dyn. 19, 159–187.Google Scholar
Halpern, D. 1976 Structure of a coastal upwelling event observed off Oregon during July 1973. Deep Sea Res. 23, 495–508.Google Scholar
Halpern, D. 1977 Description of wind and of upper ocean currents and temperature variation on the Continental Shelf off Northwest Africa during March and April 1977. J. Phys. Oceanogr. 1, 422–430.Google Scholar
Hart, J. E. 1972 A laboratory study of baroclinic instability. Geophys. Fluid Dyn. 3, 181–209.Google Scholar
Hart, J. E. 1980 An experimental study of nonlinear baroclinic instability and mode selection in a large basin. Dyn. Atmos. Oceans 4, 115–135.Google Scholar
Hide, R. 1971 Laboratory experiments of free thermal convection in a rotating fluid subject to a horizontal temperature gradient and their relation to the theory of the global atmospheric circulation. The Global Circulation of the Atmosphere, pp. 196–221. Roy. Meteror. Soc. and Amer. Meteror. Soc.
Huyer, A., Smith, R. L. & Hickey, B. M. 1984 Observation of a warm-core eddy off Oregon, January to March, 1978. Deep-Sea Res. 31, 97–117.Google Scholar
Kantha, L. H., Phillips, O. M. & Azad R. S. 1977 On turbulent entrainment at a stable density interface. J. Fluid Mech. 79, 753–768.Google Scholar
Killworth, P. D., Paldor, N. & Stren, M. 1984 Wave propagation and growth on a surface front in a two-layer geostrophic current. J. Mar. Res. 42, 761–785.Google Scholar
Linden, P. F. & van Heijst, G. J. F. 1984 Two-layer spin up and frontogenesis. J. Fluid Mech. 143, 69–94.Google Scholar
Maxworthy, T. 1977 Topographic effects in rapidly-rotating fluids: flow over a transverse ridge. Z. angew. Math. Phys. 28, 853–864.Google Scholar
Maxworthy, T. & Narimousa, S. 1985 Experiments and observations on the effects of bottom topography on coastal upwelling. Symp. on Vertical Motion in the Equatorial Upper Ocean and its Effects upon Living Resources and the Atmosphere, 6–10 May 1985, Paris.Google Scholar
Mooers, C. N. K., Collins, C. A. & Smith, R. S. 1976 The dynamics structure of the frontal zone in the coastal upwelling region off Oregon. J. Phys. Oceanogr. 6, 3–21.Google Scholar
Mooers, C. N. K. & Robinson, A. R. 1984 Turbulent jets and eddies in the California current and inferred cross-shore transports. Science 223, 51–53.Google Scholar
Narimousa, S., Long, R. R. & Kitaigorodskii, S. A. 1985 Entrainment due to turbulent shear flow at the interface of a stably stratified fluid. Tellus 38A, 76–87.Google Scholar
Narimousa, S. & Maxworthy, T. 1985 Two-layer model of shear-driven coastal upwelling in the presence of bottom topography. J. Fluid Mech. 159, 503–531.Google Scholar
Narimousa, S. & Maxworthy, T. 1986a Laboratory modeling of coastal upwelling. Transactions, American Geophysical Union EOS, 67, No. 1, 2–3.
Narimousa, S. & Maxworthy, T. 1986b Effect of a discontinuous surface stress on a model of coastal upwelling. J. Phys. Oceanogr. (in press).Google Scholar
Pedlosky, J. 1979 Geophysical Fluid dynamics. Springer.
Phillips, N. A. 1954 Energy transformations and meridional circulations associated with simple baroclinic waves in a two-level, quasi-geostrophic model. Tellus 6, 273–286.Google Scholar
Preller, R. & O'Brien, J. J. 1980 The influence of bottom topography on upwelling off Peru. J. Phys. Oceanogr. 10, 1377–1398.Google Scholar
Riencker, M. M., Mooers, C. N. K., Hagan, D. E. & Robinson, A. R. 1985 A cool anomaly off Northern California: an investigation using IR imagery and in situ data. J. Geophys. Res. 90, 4807–4818.Google Scholar
Simpson, J. J., Dickey, T. D. & Koblinsky, C. J. 1984 An offshore eddy in the California current system. Prog. Oceanogr. 13, 5–49.Google Scholar
Saunders, P. M. 1973 The instability of a baroclinic vortex. J. Phys. Oceanogr. 3, 61–65.Google Scholar