Semidiurnal internal tides on the amazon continental shelf

Author(s)

Gilberto Akio Oliveira Watanabe

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC)
• Defense date: 2014-02-26

Examining board members

Belmiro Mendes de Castro Filho; Mauro Cirano; Joseph Harari

• Advisor: Belmiro Mendes de Castro Filho

Abstract

Internal waves are oscillatory motions that occur within the density stratified ocean. The ones with tidal frequency are then called internal tides or baroclinic tides, and are, on several locations around the planet, responsible for strong fluxes that affect several processes, like sediment transport, mixing processes and primary production. In such a strong environment as the Amazon Continental Shelf (ACS), located at the northern brazilian coast, it\'s stratification changes considerably with time and space, accordingly with the balance between the several forcing variables present. In this region, some authors suggest that internal tides occur, however, none research have been made about it on the ACS. That being said, we propose a study on internal tides on the ACS. As we hypothesize that internal tides occur, we look forward to characterize it\'s behavior and verify it\'s intermittency on the ACS. To do so, the data collected during the AMASSedS project (A Multidisciplinary Amazon Shelf Sediment Study) is going to be analyzed. In order to characterize it, two different method were applied to obtain the baroclinic field. The first method was the definition of a modeled-based barotropic current of the ACS obtained on the literature. The second method was the application of Empirical Orthogonal Functions in order to split the field on statistical modes of variability and analyze them separately. Our results indicate that internal tides on the ACS occur preferentially on the semi-diurnal frequency and it\'s generation is intimately connected to river discharge. Also, the analysis of the salinity anomaly field indicates that internal tides are responsible for part of the variability of the later on the surface on mid-shelf. (AU)

• FAPESP's process: 11/05300-7 - Internal tides in the Amazon Continental Shelf
• Grantee: Gilberto Akio Oliveira Watanabe
• Support Opportunities: Scholarships in Brazil - Master