2023_programme: Seismic Oceanography applied to the North Atlantic Ocean

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  • Session: 22. Underwater Seismoacoustics
    Organiser(s): Nathalie Favretto-Cristini and Paul Cristini
  • Lecture: Seismic Oceanography applied to the North Atlantic Ocean
    Paper ID: 1929
    Author(s): Duarte Ana F., Amaral Inês, Peliz Álvaro, Mendes Renato, Matias Luis, Azevedo Leonardo
    Presenter: Duarte Ana
    Abstract: Seismic oceanography is a valuable tool for understanding the structure of the ocean using multichannel reflection seismic data. The acoustic response (i.e., the multichannel seismic data) depends on ocean temperature and salinity contrasts. The resulting images track the boundaries between these thermohaline layers laterally and vertically. Seismic oceanography creates high-resolution images of the ocean structure, allowing the study of fine-scale ocean processes at high-resolution along long two-dimensional sections. The structural interpretation of these seismic reflections provides valuable insights into mixing processes and other phenomena occurring at different water depths.\nA set of multichannel seismic reflection 2-D sections acquired in 2006 by the Portuguese Task Force for the Extension of the Continental Shelf in the North Atlantic Ocean were processed, interpreted and modelled to enhance the amplitudes of the water column and were analysed together with conductivity-temperature-depth (CTD) profiles from 2002 and 2005.\nThe ocean in this area is impacted by the intrusion of the Mediterranean Outflow, representing warmer and saltier water masses between 500 and 1500 m depth, ideal conditions for the development of double-diffusion, specifically thermohaline staircases, due to differences in temperature and salinity gradients. The thermohaline staircases were detected in the CTD profiles, with well-defined step structures representing the mixing interfaces. The seismic profiles showed continuous sub-horizontal reflections between 1200 and 2000 meters deep. The CTD profiles were compared with the seismic images and revealed that the staircases seen on the vertical profiles corresponded to the seismic reflections allowing its spatial mapping.\nThe analysis of the seismic sections offers insights into the lateral continuity and expression of double-diffusive thermohaline staircases and other sub-mesoscale oceanographic processes in the North Atlantic Ocean, improving our understanding of these processes.
  • Corresponding author: Ms Ana Duarte
    Affiliation: CERENA
    Country: Portugal
    e-mail:

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