The South Atlantic Ocean response to local and remote forcings

The local and remote sources of variability of the South Atlantic Ocean are investigated using a set of numerical experiments and satellite data. A global, eddy-permitting, numerical simulation is analyzed to investigate the dynamical links between the Antarctic Circumpolar Current (ACC) and the Mal...

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Bibliographic Details
Main Author: Fetter Filho, Antonio F. H.
Other Authors: Matano, Ricardo P., Barth, Jack, Chelton, Dudley, Strub, Ted, Thomann, Enrique, Ross, Andrew, College of Oceanic and Atmospheric Sciences, Oregon State University. Graduate School
Format: Doctoral or Postdoctoral Thesis
Language:English
unknown
Published: Oregon State University
Subjects:
Online Access:https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/td96k481c
Description
Summary:The local and remote sources of variability of the South Atlantic Ocean are investigated using a set of numerical experiments and satellite data. A global, eddy-permitting, numerical simulation is analyzed to investigate the dynamical links between the Antarctic Circumpolar Current (ACC) and the Malvinas Current (MC). The model results indicate that the correlation between the transports of those two currents is degraded by the presence of high-frequency oscillations of the ACC at the Drake Passage. These anomalies, upon reaching the bifurcation point of the ACC do not follow the coast of South America, instead, they follow the part of the transport that flows along the Polar Front, and therefore, never reaches the MC. A distinct oscillation with a period of 150 days is found. The oscillation seems to originate west of the Drake Passage and propagates along both branches of the ACC. It is shown that anomalies of similar period are also found in altimetry data. A Principal Estimator Pattern analysis suggests that the transport of the ACC and the MC are forced by wind stress curl anomalies over the South Pacific Ocean. It also suggests that the wind stress over the Indian sector might also be important to the variability of these two currents. A series of numerical simulations are run to investigate the influence of the winds over the Southern Hemisphere on the circulation of the South Atlantic Ocean. The analysis of the experiments reveals that the ocean anomalies of the South Atlantic Ocean forced by the local winds ('local' refers to the winds over the South Atlantic Ocean) are restricted to the region north of the Polar Front. On the western boundary, there is a strong response of the Brazil Current (BC) to the local forcing, but the MC is not affected by it. The remotely forced sea surface height (SSH) anomalies that influence the variability of the South Atlantic Ocean are characterized by two SSH maxima over the `hot spots' of the Southern Ocean: the abyssal, resonant modes over the Australian-Antarctic ...