Feature-oriented acoustic tomography for coastal ocean observatories

TitleFeature-oriented acoustic tomography for coastal ocean observatories
Publication TypeJournal Article
Year of Publication2013
AuthorsCarriere O, Hermand J.P
JournalIeee Journal of Oceanic Engineering
Date Published2013/07
Type of ArticleArticle
ISBN Number0364-9059
Accession NumberWOS:000321925500012
Keywordsalgorithms; Coastal acoustic tomography; field; Fronts; geoacoustic inversion; inversion; Kalman filter; model; propagation; random walk; range dependent; sequential Bayesian filtering; shallow-water; single hydrophone; thermal front; Upwelling

The deployment of coastal observatories motivates the development of acoustic inversion schemes able to characterize rapidly time-varying range-dependent environments. This paper develops feature models as parameterization schemes for the range-dependent temperature field, when the latter is mainly influenced by an identified oceanic feature, here thermal fronts. The feasibility of feature-oriented acoustic tomography (FOAT) is demonstrated in two cases of coastal thermal front known to occur regularly: the Ushant tidal front, France (48.5 degrees N, 5 degrees E), and the Cabo Frio coastal upwelling, Brazil (23 degrees S, 42 degrees W). Realistic scenarios simulated with regional circulation models provide typical environmental variations for testing the validity of the FOAT approach, with both global optimization and sequential filtering of the (synthetic) full-field acoustic data. Matched-field processing at multiple frequencies is used to reduce ambiguities between parameters and to achieve a good tradeoff between robustness and sensitivity. The proposed feature-model parameterization is shown to provide robust estimates of the 2-D temperature field even when the simulated environment presents smaller scale inhomogeneities. Moreover, the sequential filtering based on a random walk model of the thermal front parameters enables a stable tracking of typical temperature field variations along several days. This sequential approach is particularly convenient for continuous, long-term monitoring operated with bottom-moored ocean observatories.

Short TitleIEEE J. Ocean. Eng.
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