Banca de QUALIFICAÇÃO: ÚRSULA MARTIN DAMASCENO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ÚRSULA MARTIN DAMASCENO
DATE: 21/03/2022
TIME: 14:00
LOCAL: videoconferencia
TITLE:

Hydrodynamics in submarine canyons on the continental shelf of Rio Grande do Norte

KEY WORDS:

submarine canyons; western boundary current; continental slope; equatorial margin

PAGES: 49
BIG AREA: Ciências Exatas e da Terra
AREA: Oceanografia
SUBÁREA: Oceanografia Física
SPECIALTY: Interação do Oceano com o Leito do Mar
SUMMARY:

Abstract (english): Physical processes at continental margins control the transport of heat, sediments, chemical compounds, and nutrients between the ocean basin and the continental shelf, which affects the ecosystems nearby. The shelf-edge submarine canyons interact with the currents and are potential flow-channelers between the coastal zones and the oceanic basin. Despite the importance of these phenomena, canyon-flow interactions in low latitudes of the Atlantic Ocean are poorly understood. This work aims to characterize the hydrodynamic processes in the Northeastern Brazilian continental margin, particularly in submarine canyons and shelfbreak zones of Rio Grande do Norte (RN) state. The physical processes are investigated using the Coastal Regional Oceanic Community Model (CROCO). The first analysis that will be presented here refers to the Natal canyon and was developed in CROCO using regional bathymetry interpolated from nautical charts and global databases and validated with in situ data. The model’s analysis was performed for the components of velocity (u, v and w), temperature and salinity in June and October. The horizontal analysis was performed for 0m, 45m and 60m depths, and the vertical for 5 sections spatially distributed on the outside (2) and inside (3) areas of Natal canyon. The results show that the regional hydrodynamics is mainly controlled by the interaction of the North Brazilian Undercurrent (NBUC) with bathymetry and improved by the trade winds, generating parallel counter-rotating vortices. This phenomenon disturbs the mixed layer, and its effects are observed in the permanent vertical oscillations of the thermocline and halocline. The presence of the Natal Canyon reduces the length scale of the flow and increases the local Rossby number, which results in cross-isobath flow and part of the NBUC reaches the outer shelf by the canyon’s head. These interactions form an anti-cyclonic eddy inside the canyon during June and a counterclockwise circulation during October. The zonal component of the velocity indicates that the outer shelf hydrodynamics is preferentially towards offshore. The analysis of velocity components within the canyon also showed a preferential flow towards the abyssal plain in both months. The next steps consist of performing a model for the Açu canyon (northern margin) using high-resolution bathymetry and current data, to analyze the hydrodynamic processes at the edge of the Potiguar Eddy and compare with the processes of the eastern margin. Finally, this study is expected to clarify physical processes involving submarine canyons in low latitudes of the western South Atlantic corner.

BANKING MEMBERS:
Interna - 2218779 - HELENICE VITAL
Externo ao Programa - 2276514 - MARCIO MACHADO CINTRA
Externo à Instituição - MARCUS ANDRÉ SILVA - UFPE
Presidente - 2042405 - MOAB PRAXEDES GOMES