UACE2017 Proceedings: Acoustic tomography in the Canary Basin: Meddies and Tides

• Session:
  Ocean Acoustic Tomography - Various application and data
• Paper:
  Acoustic tomography in the Canary Basin: Meddies and Tides
• Author(s):
  Brian Dushaw, Fabienne Gaillard, Thierry Terre
• Abstract:
  An acoustic propagation experiment over 308-km range conducted in the Canary Basin in 1997-1998 was used assess the ability of ocean acoustic tomography to measure the flux of Mediterranean water and Meddies. Instruments on a mooring adjacent to the acoustic path measured the passage of a strong Meddy. Over 9-months of transmissions, the arrival pattern was an initial broad stochastic pulse varying in duration by 250 to 500 ms, followed eight stable, identified ray arrivals. Small-scale sound speed variations of Mediterranean water along the sound channel axis caused acoustic scattering. Simulations showed the main effect of a Meddy passing across the acoustic path is the formation of additional early arriving rays, but these rays are thoroughly scattered by the small-scale Mediterranean water fluctuations. The dominant acoustic signature of a Meddy is therefore the expansion of the width of the initial stochastic pulse. While this signature appears inseparable from the other effects of Mediterranean water in this region, the acoustic time series indicate the steady passage of Mediterranean water across the acoustic path. Tidal variations in the travel times from mode-1 internal tides were predicted by a recent global model for such tides derived from satellite altimetry.\n
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Contact details

• Contact person:
  Dr Brian Dushaw
• e-mail:
  
• Affiliation:
  NERSC
• Country:
  Norway