Western boundary currents flow along the continents until they eventually separate and turn eastward. Observations show that the separation of some boundary currents is not stationary and occurs in different locations at different times. There is an observational indication that migrations of the separation latitude of western boundary currents are related to changes in their transports. The mechanism of this relationship is yet poorly understood. / We investigate the along-shore drift of a western boundary current separation with a nonlinear reduced gravity model on an f-plane. We consider separation due to a collision with an opposing current. It is shown that, for such a case, stationary collision and separation is possible only for boundary currents with "balanced" transports, i.e., equal near-wall depths. We perturb this solution with a small step-like variation of the transport of the opposing current and focus on the resulting time-dependent flow. / In the first part of the study, we use two different analytical methods to compute the separation latitude's migration rate. The first method involves integrated balances and the second involves the path equation for the separated flow. Using the first approach, it is found analytically that the flow consists of one current intruding into the area occupied by the other. A fully developed intrusion (at $t\rightarrow\infty)$ is steadily propagating. Using the asymptotic expansion based on the scale analysis, we derive the formulae for the migration speed and the width of the steadily propagating intrusion. Using the second approach, the original initial value problem is reduced to a single time-dependent path equation for the separated current. It is shown analytically that, as should be the case, in the limit $t\rightarrow\infty$ the path equation solution is identical to the earlier solution for the steadily propagating intrusion. / In the second part of the study, we use a nonlinear primitive equation numerical model to simulate the collision of boundary currents. A good agreement is found between the asymptotic analytical theory and complete nonlinear numerical solutions. / Application of the theory to the South Atlantic Confluence zone is discussed. It is suggested that variations of the transports of the Brazil and Malvinas currents may be important for observed migrations of the Brazil-Malvinas confluence. / Source: Dissertation Abstracts International, Volume: 57-01, Section: B, page: 0212. / Major Professor: Doron Nof. / Thesis (Ph.D.)--The Florida State University, 1995.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77651 |
| Contributors | Lebedev, Ivan., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 86 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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