Publication Date:
2022-05-25
Description:
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution October 1982
Description:
Four different problems concerning Gulf Stream Rings are
considered. The first deals with the particle trajectories of, and
advection-diffusion by, a dynamic model of a Ring. It is found that the
streaklines computed from the assumptions that the Ring is a steadily
propagating and permanent form structure accurately describe its
Lagrangian trajectories. The dispersion field of the Ring produces
east-west asymmetries in the streaklines, not contained in earlier
kinematic studies, which are consistent with observed surface patterns.
In the second problem, we compute the core mixed layer evolution of both
warm and cold Rings, and compare them to the background SST, in an
effort to explain observed SST cycles of Rings. We demonstrate that
warm Rings retain their anomalous surface identity, while cold Rings do
not, because of differences in both the local atmospheric states of the
Sargasso and the Slope and the typical mixed layer structures
appropriate to each. The third and fourth problems concern the forced
evolution of Gulf Stream Rings as effected by atmospheric interactions.
First, we compute the forced spin down of a Gulf Stream Ring. The
variations in surface stress across the Ring necessary to spin it down
are caused by the variations in relative air-sea velocity, of which the
stress is a quadratric function. From numerical simulations, we find
the forced decay rates are comparable to those inferred from Ring
observations. In the final problem, it is suggested that a substantial
fraction of meridional Ring migration is a forced response, caused by
Ring SST and the temperature dependence of stress. The warm central
waters of anticyclonic Rings are regions of enhanced stress, producing
upwelling to the north, and downwelling to the south, which shifts the
Ring to the south. A similar, southward shift is computed for cyclonic
Rings with cold centers, which tends to reconcile their numerically
computed propagation with observations.
Description:
The present research has been conducted under NOAA contract #
NA80AA-D-0057 and NSF contract II OCE-8240455
Keywords:
Ocean-atmosphere interaction
;
Ocean currents
Repository Name:
Woods Hole Open Access Server
Type:
Thesis
Format:
application/pdf
Permalink
