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Topographic Contraints on Rotating Stratified Throughflows across Large Amplitude Topography
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Topographic Contraints on Rotating Stratified Throughflows across Large Amplitude Topography. |
| 개인저자 | Jimenez-Urias, Miguel Angel. |
| 단체저자명 | University of Washington. Oceanography. |
| 발행사항 | [S.l.]: University of Washington., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 140 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781687955180 |
| 학위논문주기 | Thesis (Ph.D.)--University of Washington, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Thompson, Luanne. |
| 이용제한사항 | This item must not be sold to any third party vendors.This item must not be added to any third party search indexes. |
| 요약 | The Atlantic inflow of warm saline waters that flow into the Nordic Seas is strongly steered by the Greenland-Scotland Ridge (GSR). Such flow is associated with the lateral exchange of watermasses between the North Atlantic and the Arctic Mediterranean and is part of the large scale overturning circulation of the ocean. This thesis examines, through the use of idealized, process-based modelling, aspects of the topographically locked Atlantic inflow that flows across the Iceland-Faroe Ridge, the widest and shallowest gap of the GSR.The effects of bottom topography on the instability, eddy-driven heat flux and overturning of a topographically locked top to bottom front is examined in Chapter 2. Central to this study is that the surface expression of the front presents lateral shear within the mixed layer, typical of wintertime conditions. We find the initial growth of surface mixed layer eddies is insensitive to topographic variations but during the finite amplitude phase of mixed layer instability, we find faster development of mesoscale eddies and stronger cross-front eddy heat flux in the cases where the frontal jet experiences the most destabilizing bottom topography of the three cases tested, with values comparable to the heat flux associated with the mean flow. Therefore, eddy dynamics over the IFR frontal region are important contributors to the heat exchanges between the North Atlantic and Nordic Seas, with bottom the topography playing a key role in determining the largest heat fluxes, whether the initial growth is dominated by mixed layer eddies, or mesoscale eddies.Chapter 3 examines the leading order balance that determine the transport pathwaysassociated with throughflows across a symmetric, large amplitude ridge. The equilibrated circulation across the ridge is characterized by an anticyclonic boundary current associated with northward upslope transport and a cyclonic boundary current associated with north- ward downslope transport, with a strong near bottom stratification associated with the anticyclonic boundary current and low stratification associated with the cyclonic boundary current. Such along-stream stratification implies a nearly the northward upslope transport experiences little resistance by the ridge, and a cyclonic boundary current that requires a stronger inertial recirculation to promote downslope northward transport. The observed difference in baroclinic behavior across the ridge crest may explain the preferred cyclonic circulation and strong along-slope topographic steering experienced by Atlantic waters as they flow north of the Greenland Scotland Ridge.Chapter 4 examines the baroclinic structure of throughflows across a finite amplitude ridge. We find that bottom Ekman dynamics localized to lateral boundary currents restratify the bottom boundary layer, resulting is strongly stratified front (thus a high PV anomaly) along the anticyclonic boundary current, and a low stratified (vanishingly low PV) mixed layer front localized to the cyclonic boundary current. These PV anomalies are advected by both the mean flow and eddies that result from baroclinic instability of the mean flow, resulting in a spatial distribution where high PV is concentrated along the ridge, and low PV is advected into the interior, mid depth ocean downstream from the ridge. Using a framework of volume integrated PV conservation which incorporates the net fluxes associated with bottom topography we conform this approximate integral balance between the injection of low PV from the bottom boundary layer downstream from the ridge and net advective across the ridge. Implications of these findings for understanding the interplay between large scale and bottom boundary dynamics are discussed. |
| 일반주제명 | Physical oceanography. |
| 언어 | 영어 |
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