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Detailed Reference Information |
Zhang, X., McGuinness, D.S. and Boyer, D.L. (1994). Narrow barotropic currents impinging on an isolated seamount. Journal of Geophysical Research 99: doi: 10.1029/94JC01569. issn: 0148-0227. |
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Laboratory and numerical experiments concerned with the interaction of homogeneous narrow currents (jets) and tall, isolated topographic features in the presence of background rotation were conducted. The laboratory jets (in an azimuthal direction) were produced in a rotating circular test cell using a circularly symmetric, free surface, source sink technique. By regulating the Rossby and Ekman numbers of the jets, the narrow currents so created can be either circularly symmetric (stable) or meandering (unstable). A theoretical analysis for a point sink at the test cell center is advanced to predict the strength and radial distribution of the azimuthal current in the absence of bottom topography. Laboratory observations are found to be in good agreement with the model. The interaction of stable currents with isolated topography was investigated. The system parameters are the Rossby and Ekman numbers, the normalized topographic width and height, the width of the current, and the position of the streamwise centerline. A numerical model was developed which employed a vertically averaged vorticity equation driven by Ekman layer forcing along the free surface and dissipated by Ekman pumping along the lower bounding surface. The model is supported by laboratory observations. Only stable currents are considered for the numerical calculations. Currents which pass either to the right or left of the obstacle center as well as those which impinge directly are considered. For all cases, anticyclonic motions are found atop the obstacle. In the numerical experiments the maximum values of cyclonic and anticyclonic vorticity above the topography are found to be monotonically increasing functions of the Rossby number, with other parameters fixed. For cases in which the current is to the right of the topographic feature, closed cyclonic vortices are formed in the left topography lee. The normalized area of these cyclones increases with increasing Rossby number, for the range of Ro investigated. For all cases the transport stream function lines in the right topography lee are deflected relatively more than the corresponding streamlines in cases for which the upstream flow is uniform and rectilinear (i.e., a broad current having no relative upstream vorticity). |
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Abstract |
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Keywords
Oceanography, Physical, Coriolis effects, Oceanography, Physical, Currents, Oceanography, Physical, Eddies and mesoscale processes |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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