2025_programme: The future evolution of mid-frequency active sonar performance in a changing ocean

• Day: June 19, Thursday
    Location / Time: B. ERATO at 12:00-12:20
• Last minutes changes: -
• Session: 16. Sonar performance modeling and verification: Active and passive sonar
  Organiser(s): Mathieu Colin, Kevin Heaney
  Chairperson(s): Kevin Heaney, Victor Oppeneer
• Lecture: The future evolution of mid-frequency active sonar performance in a changing ocean
  Paper ID: 2329
  Author(s): Xavier Cristol, Bruno Chalindar, Nicolas Fisichella, Herald Rabeson
  Presenter: XAVIER CRISTOL
  Abstract: Climate change and global political-economic developments affect the future performance of underwater acoustic instruments through several interrelated channels: changes in sound velocity profile and volume attenuation in a physically evolving ocean, combined with a likely increase in ambient noise from shipping traffic and route changes. This multifactorial problem has already been the subject of several published analyses, with controversial conclusions. \nClimate change is primarily driven by changing atmospheric CO2 concentration; for this parameter, we have adopted the IPCC's Shared Socio-Economic Trajectory SSP5-8.5, which is the most pessimistic, but apparently the most probable curve. The variations of physical ocean parameters over the 21st century have been the subject of numerous models, the results of which are available online: 120 models were compared in the Coupled Model Intercomparison Project - Phase 6 (CPIM6). We have chosen the predictions of the ocean climate model CNRM-ESM2, developed by the CNRM (Toulouse, France), which not only has a good reputation, but also lies in the middle of the very different trends proposed by the 120 models analyzed by CMIP6.\nIn this article, we present preliminary global conclusions based on a planetary-scale analysis of the evolution of the various terms of the Sonar Equation, along with the tactical behavior of sonar use. We restrict ourselves to a generic fictitious active VDS (Variable Depth Sonar) sonar operating in the mid-frequency range 1-10kHz. Global 1°latitude x1° longitude maps of maximum detection ranges are presented. Apart from some local variations, simple and somewhat counterintuitive trends emerge for the period 2019-2100: in both the northern and southern hemispheres, detection ranges remain stable in winter and tend to increase with time in summer, as a result of the contradictory interplay between changes in the shape of velocity profiles (accentuation of permanent and seasonal thermoclines) and reductions in volume absorption.\n
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• Corresponding author: Dr XAVIER CRISTOL
  Affiliation: Thales Defence Mission Systems
  Country: France