Tracking cold water upwelling filaments in the ocean using matched-field inversion

V. Corré
S.M. Jesus
SiPLAB-FCT, Universidade do Algarve,
Campus de Gambelas,
PT-8000 Faro, Portugal.

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Ref.: Acta Acustica united with Acustica, Vol. 89, p. 604-613,  2003.

A new application of a matched-field inversion method for estimating the range and time variability of ocean properties is presented. The method uses acoustic data from a single array-source pair. Since estimating range-dependent properties with such a simple configuration is a problem which solution may not be unique, the primary objective is to obtain the variability trend rather than very accurate estimates of the properties. The inversion method is applied to a synthetic data set obtained during the simulated development of an upwelling filament. The objective consists in estimating the sound-speed profile of the filament, its position and width, and the variations of these properties with time. The performance of the method is first tested in the ideal case where no noise nor model mismatch is present. Results show the feasibility of tracking the upwelling and obtaining good accuracy for the parameter estimates wihtin a reasonable computation time. The presence of noise in the data or model mismatch degrades the accuracy of the parameter estimates. However the global rise of cold water can still be detected and localized under realistic conditions. Although the filament properties as well as the source and array positions have noticeable effects on the inversion results, no clear evidence of a parameter hierarchy was found.