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Is the Cromwell current driven by equatorial Rossby waves?

Published online by Cambridge University Press:  28 March 2006

Walter Munk  and
Dennis Moore
Walter Munk
Affiliation:
Departments of Meteorology and Geology and Geophysics, Massachusetts Institute of Technology
On sabbatical leave from the Institute of Geophysics and Planetary Physics, University of California, San Diego, La Jolla, California.
Dennis Moore
Affiliation:
Division of Engineering and Applied Physics, Harvard University
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Abstract

A second-order theory for equatorial, baroclinic Rossby waves in a bounded ocean yields, among other components, terms of zero frequency. We inquire whether the associated rectified flow (or ‘streaming’, or ‘mass transport’) can be related to the submerged equatorial jet observed by Cromwell, Knauss and others. For quite reasonable models of baroclinic Rossby waves, the resultant streaming can be sharply concentrated at the equator, and varies in depth as N(z), thus giving maximum flow at the thermocline (where the Väisälä frequency N(z) is largest). In this way the rectification hypothesis might account for the observed submerged equatorial steering of the Cromwell current. The observed direction of streaming calls for a predominance of equatorially symmetric Rossby waves. The observed magnitude implies that the r.m.s. fluctuations be of the same order as the mean current; that is to say, we have applied weakinteraction theory to a strong-interaction problem. There are other difficulties.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 33 , Issue 2 , 12 August 1968 , pp. 241 - 259
Copyright
© 1968 Cambridge University Press

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References

Blandford, R. 1966 Mixed gravity-Rossby waves in the ocean Deep-Sea Res. 13, 941–61.Google Scholar
Cox, C. S. & Sandstrom, H. 1962 Coupling of internal and surface waves in water of variable depth. J. Oceangr. Soc. Japan, 20th Anniv. Vol.Google Scholar
ERDELYI, 1953 Higher Transcendental Function, vol. II. New York: McGraw-Hill.
Groves, G. 1965 Doctoral thesis. Scripps Institution of Oceanography.
Knauss, J. A. 1960 Measurements of the Cromwell current. Deep-Sea Res. 6, (4), 265–85.Google Scholar
Knauss, J. A. 1966 Further measurements and observations on the Cromwell current J. Mar. Res. 24, 205–40.Google Scholar
LONGUET-HIGGINS, M. S. 1964 Planetary waves on a rotating sphere, I. Proc. Roy. Soc A 279, 446–73.Google Scholar
LONGUET-HIGGINS, M. S. 1965 Planetary waves on a rotating sphere, II. Proc. Roy. Soc A 284, 40–54.Google Scholar
Matsuno, T. 1966 Quasi-geostrophic motions in the equatorial area. J. Met. Soc. Japan II 44, 25–43.Google Scholar
Metcalf, W. G., Voorhis, A. D. & Stalcup, M. C. 1962 The Atlantic equatorial undercurrent J. Geophys. Res. 67, 2499–508.Google Scholar
Montgomery, R. B. & Stroup, E. D. 1962 Equatorial water and currents at 150° west in July-August 1952. Johns Hopkins Oceanogr. Stud. I, 68 pp.Google Scholar
Pedlosky, J. 1965 A study of the time dependent ocean circulation J. Atmos. Sciences 22, 267–72.Google Scholar
Phillips, N. 1966 Large-scale eddy motion in the Western Atlantic J. Geophys. Res. 71, 3883–91.Google Scholar
Rattray, M. & Charnell, R. L. 1966 Quasi-geostrophic free oscillations in enclosed basins J. Mar. Res. 24, 82–103.Google Scholar
Reid, J. L. 1964 A transequatorial Atlantic oceanographic section in July, 1963 compared with other Atlantic and Pacific sections J. Geophys. Res. 69, 5205–16.Google Scholar
Robinson, A. R. 1965 Chapter 17 of Research Frontiers in Fluid Dynamics, pp. 504–33. New York: Interscience.
Robinson, A. R. 1966 An investigation into the wind as the cause of the equatorial undercurrent J. Mar. Res. 24, 179–204.Google Scholar
Sverdrup, H. U. 1947 Wind-driven currents in a baroclinic ocean, with application to the equatorial currents of the eastern Pacific Proc. Natn. Acad. Sci. U.S.A. 33, 318–26.Google Scholar