Thesis (M.S.)--Joint Program in Oceanography/ Applied Ocean Science and Engineering, Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 2006. / "September 2006." Bibliography: p. 97-106.

Preliminary results of a two-layer quasi-geostrophic box model of a wind-driven ocean are presented. The new aspects of this work in relation with conventional eddy models are a finite element formulation of the quasi-geostrophic equations and the use of no-slip boundary condition on the horizontal solid boundaries. In contrast to eddy resolving models that utilize free-slip boundary conditions our results suggest that the obtention of ocean eddies with the no-slip constraints requires a more restricted range of parameters, in particular much lower horizontal eddy viscosity eddy coefficients AH and higher Froude numbers F₁ and F₂. We show explicitly that a given range of parameters, which is eddy generating when the free-slip boundary condition is used, leads to a quasi-laminar flow in both, upper and lower, layers. An analytical model to interpret the numerical results is put forth. It is an extension of an earlier model of Ierley and Young (1983) in that the relative vorticity terms are of primary importance for the dynamics. Thus, it is shown that the boundary layer dynamics is active in the interior of the second layer, and it can be concluded from our method that for given F₁ and F₂ such that the lower layer geostrophic contours are closed, to the existence of the western boundary layer will prevent the homogenization of the potential vorticity so long as AH is large enough to stabilize the northwestern undulations of the flow. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

No description available.

The use of an ocean surface velocity dependent wind stress is examined in the context of a 3-layer double-gyre quasigeostrophic wind-driven ocean circulation model. The new wind stress formulation results in a large reduction of the power input by the wind into the oceanic circulation. This wind stress is proportional to a quadratic function of Ua--u o, where Ua is the wind at 10m above the ocean surface and uo is the ocean surface current. Because the winds are typically faster than the ocean currents, the impact of the ocean surface velocity on the wind stress itself is relatively small. However, the power input is found to be greatly reduced with the new formulation. This is shown by simple scaling argument and numerical simulations in a square basin. Our results suggest that the wind power input may be as much as 35% smaller than is typically assumed. / The ocean current signature is clearly visible in the scatterometer-derived wind stress fields. We argue that because the actual ocean velocity differs from the modeled ocean velocities, care must be taken in directly applying scatterometer-derived wind stress products to the ocean circulation models. This is not to say that the scatterometer-derived wind stress is not useful. Clearly the great spatial and temporal coverage make these data sets invaluable. Our point is that it is better to separate the atmospheric and oceanic contribution to the stresses. / Finally, the new wind stress decreases the sensitivity of the solution to the (poorly known) bottom friction coefficient. The dependence of the circulation strength on different values of bottom friction is examined under the standard and the new wind stress forcing for two topographic configurations. A flat bottom and a meridional ridge case are studied. In the flat bottom case, the new wind stress leads to a significant reduction of the sensitivity to the bottom friction parameter, implying that inertial runaway occurs for smaller values of bottom friction coefficient. The ridge case also gives similar results. In the case of the ridge and the new wind stress formulation, no real inertial runaway regime has been found over the range of parameters explored.

No description available.

Graduation date: 1982

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1980. / Microfiche copy available in Archives and Science. / Bibliography: leaves 85-88. / by Donald Albert Campbell. / M.S.

Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Meteorology. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 320-325. / by Mark A. Cane. / Ph.D.

Bibliography: leaves 169-178.