Diabaté, Samuel Tiéfolo (2024) Coastal sea-level changes driven by oceanic and atmospheric circulation. PhD thesis, National University of Ireland Maynooth.
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2026-Samuel Diabate Thesis.pdf
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Abstract
This thesis investigates the coastal sea-level changes driven by oceanic
and atmospheric circulation, with a focus on three ocean basin boundaries
in the northern hemisphere: the northeast Atlantic, the northwest Pacific
and the northwest Atlantic.
In a first part, the focal point is on the northeast Atlantic and
the European shelf and coastal sea level. Observations of the oceanic
circulation in the northeast Atlantic are presented, using altimetry
observations and in-situ measurements from moored instruments deployed
in the last thirty years. Together, these recent observations showcase a
poleward flow to the west of Ireland and Scotland: the Rockall Slope
Current. In contrast, I find no evidence of an upstream continuation to the
Rockall Slope Current which would form a continuous slope circulation
circumnavigating Europe. The spatial distribution of sea level induced
by an idealised eastern boundary slope circulation, representative of the
Rockall Slope Current, is then derived. Both bottom friction as well as
the joint effect of baroclinicity and relief are considered in this theoretical
study. I demonstrate how the large-scale poleward dynamic height decline
in the North Atlantic is mediated to the shelf and eventually affects the
coastal sea level thanks to the transport divergence generated by bottom
Ekman currents. Through this process, the poleward slope circulation is
slowed down. Finally, the sub-annual variability in sea level and currents is
investigated. The shelf sea-level changes are found to reflect the alignment
of the winds with the along-isobath direction. Analysis of the in-situ
current data reveals the build-up of sea level on the shelf leads to changes
in along-isobath currents on the outer-shelf and upper-slope.
In a second part, the focal point shifts to the links between subtropical
western boundary currents and sea-level variability in the northern
hemisphere. The role of the Gulf Stream and of the Kuroshio in driving
interannual changes in nearby coastal sea level are conjointly investigated.
It is found that the sea level on the Japanese and American coasts is
strongly affected by the variability of these major western boundary
currents. In particular, path changes of the western boundary currents
are responsible for important coastal sea-level variations. Coastal sea-level
changes reflect meridional shifts of western boundary currents downstream
of their separation from the continental slope. In the northwest Pacific,
meandering of the Kuroshio in the region upstream its separation point
is also a strong driver of coastal sea-level changes.
Item Type: | Thesis (PhD) |
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Keywords: | Coastal sea-level changes; oceanic circulation; atmospheric circulation; |
Academic Unit: | Faculty of Social Sciences > Geography |
Item ID: | 20078 |
Depositing User: | IR eTheses |
Date Deposited: | 25 Jun 2025 10:15 |
URI: | https://mural.maynoothuniversity.ie/id/eprint/20078 |
Use Licence: | This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here |
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