Sensitivity Analysis in Ocean Acoustic Propagation

The sensitivity of acoustic pressure to sound speed is investigated through the application of adjoint-based sensitivity analysis using an acoustic propagation model. The sensitivity analysis is extended to temperature and salinity, by deriving the adjoint of the sound polynomial function of temperature and salinity. Numerical experiments using a range dependent model are carried out in a deep and complex environment at the frequency of 300 Hz. It is shown that through the adjoint sensitivity analysis one can infer reasonable variations of sound speed, and thus temperature and salinity. Successful extension of the sensitivity of acoustic pressure to temperature and salinity implies that acoustic pressure observations in a given range-depth plane can be assimilated into an ocean model using the acoustic propagation model as the observation operator