2023_programme: Processing of multi-channel seismic data to imaging the water column in the North Atlantic Ocean
- Session: 22. Underwater Seismoacoustics
Organiser(s): Nathalie Favretto-Cristini and Paul Cristini
- Lecture: Processing of multi-channel seismic data to imaging the water column in the North Atlantic Ocean
Paper ID: 2005
Author(s): Amaral Inês, Duarte Ana F., Azevedo Leonardo, Matias Luís
Presenter: Amaral de Carvalho Inês
Abstract: Seismic oceanography was designed to understand the ocean and its role in the ecosystems, through seismic reflection method, using acoustic waves to estimate Earth’s physical characteristics with high spatial resolution. The North Atlantic Ocean is a complex structure, its currents carry the warmer waters away from the Equatorial line, helping regulate Earth’s climate. Distinct water layers with contrasting temperature and salinity values, are characteristics of fine scale thermohaline structures, that prove ocean’s mixing processes. By propagating sound waves within the water column, reflections derive from temperature and salinity contrasts, which allows to understand how different water layers interact. In 2006, EMEPC, a project that aims defending Portugal’s proposal of extending the continental shelf, acquired a set of 2D multi-channel seismic reflection sections in the North Atlantic Ocean, that after being recorded and processed, create a seismic image of the water column. In seismic oceanography, the processing of multi-channel seismic data is crucial, as it enhances the amplitude content of the water column and allows interpreting the target features accurately. After removing the noise that may have been recorded during acquisition, by applying filters that boost the desired amplitudes, data processing enables creating a high-resolution section of the ocean. To further increase the image quality, additional processes were applied, such as removing of the direct arrival, based on a horizontal median filter with subtraction, and normal moveout correction (NMO). Both are challenging steps, since the direct arrival corrupts observation of thermohaline structures in the near-offsets shallower depths, and NMO due to the velocity analysis to determine the sound speed in the water column. Finally, stacking and migrating the data, combining multiple traces from different receiver positions, to improve the signal-to-noise ratio and correct the reflectors position, it is possible to image oceanic fronts which can relate to Mediterranean water intrusions.
- Corresponding author: Ms Inês Amaral de Carvalho
Affiliation: CERENA/DER, Universidade de Lisboa, Instituto Superior Técnico
Country: Portugal
e-mail:
