UACE2025: Water column sound speed profile recovery via adjoint modelling

    • Session:
      Acoustic modelling and Inversion methods
    • Paper:
      Water column sound speed profile recovery via adjoint modelling
    • Author(s):
      Eftychia Karasmani, John S. Papadakis
    • Abstract:
      In this work, we exlpoit the adjoint optimal control method developed for geoacoustic inversions by J. S. Papadakis et al., for recovering the sound speed profile (SSP) in the water column. In particular, the direct propagation problem is modelled via the wide angle parabolic approximation (WAPE) and the cost function quantifies the discrepancy between the observed acoustic field and the field predicted by the model. A gradient descent iterative scheme is used for the minimization of the cost function. Here we assume that the SSP can be written as a linear combination of some known basis functions, thus we can calculate analytically the derivatives of the cost function with respect to the unknown coefficients which determine the amplitude of the basis functions. To assess the performance of the method, two test cases are exhibited. In the first test case an artificial example is proposed, where we use some linear basis functions. In the second test case empirical orthogonal functions (EOFs) are used. We have to point out that EOFs are coming from statistical analysis of long term observations and consist an orthogonal basis for SSPs in the western Mediterranean Sea. The estimations obtained are compared with the actual values of the parameters.
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    Contact details

    • Contact person:
      Ms Eftychia Karasmani
    • e-mail:
    • Affiliation:
      Institute of Applied and Computational Mathematics - FORTH
    • Country: