Time-Lapse Volumetric Seismic Imaging of a Major Oceanic Front and Submesoscale Coherent Vortices at South Atlantic Ocean
type: CreativeWork
description: Seismic oceanography (SO) involves deploying a ship that tows an acoustic energy source and one or more receiver cables just beneath the sea surface. Acoustic waves reflected from temperature and salinity gradients are recorded by arrays of hydrophones located along the receiver cables. Compared with standard hydrographic measurements, seismic reflection imagery provides much improved spatial resolution and extensive coverage over a whole range of length scales, enabling detailed spatial and temporal quantification of thermohaline structures and ocean mixing. Between December 2012 and April 2013, a three-dimensional (3-D) seismic survey was carried out at the Brazil-Malvinas Confluence of the South Atlantic Ocean. Each individual seismic swath is approximately 140 km long and 600 m wide. The complete survey consists of 28 seismic profiles that were analyzed using an industry-standard signal processing package. Together, these profiles image a dynamic frontal system with intense mesoscale eddy activity. During February 2013, a mesoscale front occurs as a planar surface dipping at less than two degrees. This front is traceable to a depth of nearly 2 km. Within the top 1 km, where cold fresh water subducts beneath warm salty water, several tilted lenses are observed. The largest lens, identified as a submesoscale coherent vortex (SCV), had a maximum diameter of $\sim$ 40 km and a height of $\sim$ 750 m. This SCV is associated with a negative acoustic velocity anomaly that is consistent with a cold fresh water core. Time-lapse imagery reveals its growth and decay over an 11-day period. Surface measurements confirm that the front and SCV translate at $\sim$ 0.1 m/s from northeast to southwest. A second SCV with similar scaling is observed during April 2013. It moves at a slower speed of $\sim$ 0.05 m/s. Sub-surface hydrographic measurements confirm that these imaged SCVs consist of cold and fresh water that is also characterized by low stratification and minimal horizont…
abstract: Seismic oceanography (SO) involves deploying a ship that tows an acoustic energy source and one or more receiver cables just beneath the sea surface. Acoustic waves reflected from temperature and salinity gradients are recorded by arrays of hydrophones located along the receiver cables. Compared with standard hydrographic measurements, seismic reflection imagery provides much improved spatial resolution and extensive coverage over a whole range of length scales, enabling detailed spatial and temporal quantification of thermohaline structures and ocean mixing. Between December 2012 and April 2013, a three-dimensional (3-D) seismic survey was carried out at the Brazil-Malvinas Confluence of the South Atlantic Ocean. Each individual seismic swath is approximately 140 km long and 600 m wide. The complete survey consists of 28 seismic profiles that were analyzed using an industry-standard signal processing package. Together, these profiles image a dynamic frontal system with intense mesoscale eddy activity. During February 2013, a mesoscale front occurs as a planar surface dipping at less than two degrees. This front is traceable to a depth of nearly 2 km. Within the top 1 km, where cold fresh water subducts beneath warm salty water, several tilted lenses are observed. The largest lens, identified as a submesoscale coherent vortex (SCV), had a maximum diameter of $\sim$ 40 km and a height of $\sim$ 750 m. This SCV is associated with a negative acoustic velocity anomaly that is consistent with a cold fresh water core. Time-lapse imagery reveals its growth and decay over an 11-day period. Surface measurements confirm that the front and SCV translate at $\sim$ 0.1 m/s from northeast to southwest. A second SCV with similar scaling is observed during April 2013. It moves at a slower speed of $\sim$ 0.05 m/s. Sub-surface hydrographic measurements confirm that these imaged SCVs consist of cold and fresh water that is also characterized by low stratification and minimal horizont…
author: Chen, Xiaoqing
language: eng
keywords: Diapycnal Mixing, Seismic Oceanography, Submesoscale Coherent Vortices
license: https://www.repository.cam.ac.uk/bitstreams/d46af6b8-6ae3-43b2-a8f5-0c1501251eea/download
license: http://purl.org/NET/rdflicense/allrightsreserved
date published: 2024-09-16
date modified: 2026-07-22T22:23:56Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.115405