2025_programme: Decadal observations of deep ocean temperature change passively probed with acoustic waves

• Day: June 16, Monday
    Location / Time: A. TERPSIHORI at 12:20-12:40
• Last minutes changes: -
• Session: 04. Comprehensive Nuclear-Test-Ban Treaty Monitoring, and its Civil and Scientific Applications
  Organiser(s): Georgios Haralabus, Mario Zampolli, Tiago Oliveira, Mark Prior
  Chairperson(s): Georgios Haralabus, Tiago Oliveira
• Lecture: Decadal observations of deep ocean temperature change passively probed with acoustic waves [Invited]
  Paper ID: 2128
  Author(s): Läslo Evers
  Presenter: Läslo Evers
  Abstract: The oceans are filled with acoustic waves, which are trapped in a low-velocity layer at about 1 km water depth. The sound speed of these waves strongly depends on the temperature. An increase in temperature will lead to an increase in the sound speed and hence shorter travel times. Hydro-acoustic stations measure these waves continuously and travel times can be obtained through the cross correlation of transient signals between different hydrophones. CTBTO's IMS hydro-acoustic station H10 near Ascension Island has been operational for nearly two decades. Although in place to detect nuclear-test explosion, IMS station H10 appeared well equipped to measure deep ocean temperature change. A decrease in the travel time between the two arrays was derived, being -0.002 s/yr. This corresponds to a deep ocean warming of 0.007 degC/yr, at about 900m water depth. As such, acoustic waves provide an independent and passively acquired measure of the temperature change in the deep ocean.
• Corresponding author: Mr Läslo Evers
  Affiliation: KNMI / TU Delft
  Country: Netherlands