Authors

Citation

Xz. Zhang et al., MEAN FLOW GENERATION ALONG A SLOPING REGION IN A ROTATING HOMOGENEOUSFLUID, J GEO RES-O, 101(C12), 1996, pp. 28597-28614

Citations number

27

Language

INGLESE

art.tipo

Article

Categorie Soggetti

Oceanografhy

Journal title

JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS

ISSN journal

2169-9275
â†’ ACNP

Volume

101

Issue

C12

Year of publication

1996

Pages

28597 - 28614

Database

ISI

SICI code

2169-9275(1996)101:C12<28597:MFGAAS>2.0.ZU;2-E

Abstract

The mean flow generated by an oscillatory (tidal) current normal to a
long sloping region of constant cross section and finite height in a r
otating homogeneous fluid is investigated analytically and by laborato
ry experiments. The geometry is characterized by constant fluid depths
h(s) and h(d) in the shallow (shelf) and deep regions, respectively,
with the sloping region between being smooth and having a characterist
ic width L. This physical system is characterized by the temporal Ross
by number Ro(t) = omega/f, the Ekman number E, the geometric parameter
s h(s)/h(d) and h(s)/L, and the normalized tidal excursion a(s)/L (or,
alternatively, the Rossby number); here omega is the forcing frequenc
y of the oscillatory current, f is the Coriolis parameter, and a(s) is
the characteristic tidal excursion. The analysis assumes Ro(t) simila
r to O(1), E much less than 1, h(s)/L much less than O(1), (h(d) - h(s
))/h(d) similar to O(1) (i.e., finite amplitude topography), and a(s)/
L similar to O(1) (i.e., finite amplitude tidal excursions). The analy
sis is based upon a spectral method [Zimmerman, 1978] and predicts mea
n flows along the depth contours of the topography with the shallow re
gion on the right, facing downstream, for vertically upward, or northe
rn hemisphere, rotation. The theoretical approaches used by other inve
stigators using different frictional parameterizations for infinitesim
al tidal excursions are also presented. The laboratory experiments wer
e conducted in circular rotating test cells of 1.8 and 13.0 m diameter
s in which continuous annular topographies of constant cross section w
ere installed along the tank peripheries. The various theories were in
qualitative support of the laboratory observations with respect to (1
) mean flow direction, (2) location of most intense currents, and (3)
dependence on the principal system parameters. Owing to the very small
velocities associated with the mean flows generated and the inherent
errors of the experiments, quantitative comparison could not be conclu
sive. Predictions from the various theories give reasonable estimates
of such quantities as mean Lagrangian displacements and Eulerian surfa
ce transports.